WEIGHTS and

MEASURES

STANDARDS

OF THE

UMIT

a brief history

U.S. DEPARTMENT OF COMMERCE

NATIONAL BUREAU OF STANDARDS

NBS Special Publication 447

WEIGHTS and

MEASURES

STANDARDS

OF THE

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NBS Special Publication 447

Originally Issued October 1963

Updated March 1976

For sale by the Superintendent of Documents, U.S. Government Printing Office Wash., D.C. 20402. Price $1; (Add 25 percent additional for other than U.S. mailing). Stock No. 003-003-01654-3
Library of Congress Catalog Card Number: 76-600055
Foreword

"Weights and Measures," said John Quincy Adams in 1821, "may be ranked among the

necessaries of life to every individual of human society." That sentiment, so appropriate to the

agrarian past, is even more appropriate to the technology and commerce of today. The order that we enjoy, the confidence we place in weighing and measuring, is in large part due to the measure- ment standards that have been established. This publication, a reprinting and updating of an earlier publication, provides detailed information on the origin of our standards for mass and length.

Ernest Ambler

Acting Director

iii
Preface to 1976 Edition

Two publications of the National Bureau of Standards, now out of print, that deal with

weights and measures have had widespread use and are still in demand. The publications are NBS

Circular 593, The Federal Basis for Weights and Measures (1958), by Ralph W. Smith, and NBS

Miscellaneous Publication 247, Weights and Measures Standards of the United States—a Brief

History (1963), by Lewis V. Judson.

To meet the current demand for information on the history of weights and measures in the

United States, Miscellaneous Publication 247, referred to above, updated where needed to bring it into accord with current usage, is reprinted in this Special Publication, together with a brief addendum that discusses important events involving weights and measures of the period 1963-

1975, immediately following the original date of publication of MP 247. NBS Circular 593 is not

being reprinted because of the significant overlap of material treated in the two publications.

Those interested in a detailed account of the Federal legislative background in the field of weights

and measures units and standards should refer to NBS Circular 593 in one of the more than 100

depository libraries throughout the country.

Louis E. Barbrow

PreFace to 1963 Edition

In 1905, Louis A. Fischer, then a distinguished metrologist on the staff of the

National Bureau of Standards, presented a paper entitled "History of the Standard

Weights and Measures of the United States" before the First Annual Meeting of

the Scalers of Weights and Measures of the United States. This paper quickly came

to be considered a classic in its field. It was published by the National Bureau of

Standards several times— most recently in 1925 as Miscellaneous Publication 64. For some time it has been out of print and in need of up-to-date revision. The

present publication covers the older historical material that Fischer so ably treated;

in addition, it includes a brief summary of important later developments affecting

the units and standards for length and mass. (Liberal use of Mr. Fischer's text is made in this publication.)

Lewis V. Judson .

iv
Conttnts

Page

Foreword iii Preface IV

1. Introduction 1

2. Early history of weights and measures in the United States 2

3. Units and standards 6

4. Early United States standards 6

5. Use of metric system officially permitted 10

6. International standards of weights and measures 13

7. The Mendenhall Order 16

8. Refinement of values for the yard and pound 20

9. Wavelength definition of the meter 21

10. Other definitions of imits 21

11. Current and historical standards of length and mass at the National

Bureau of Standards 21

12. Addendum (The period 1963-1975) 25

Appendix 1. Bibliography 27

Appendix 2. Report on the troy pound of the Mint 27

Appendix 3. The Mendenhall Order of April 5, 1893 28

Appendix 4. The international nautical mile 29

Appendix 5. The U.S. yard and pound 30

Appendix 6. Adoption of the wavelength definition of the meter 31

Appendix 7. Metric system of weights and measures (Federal Register

Notice of June 19, 1975) 33 Appendix 8. Gjmmercial weights and measures units (Federal Register

Notice of July 27, 1968) 34

Appendix 9. Commercial weights and measures units (Federal Register

Notice of February 3, 1975) 36

V

Weights and Measures Standards of the United States

o brief history

Lewis V. Judson

A historical account is given of the standards of weights and measures of the United States from the time of the American Revolution through the year 1962.* Current and historical standards of length and mass now in the possession of the National Bureau of Standards are listed and described.

1. Introduction

When a housewife buys a quart of milk, when a midwestern farmer sells his grain crop—in all present-day

commercial transactions—there is an implied faith

that as goods are exchanged for money there is the same just balance for buyer and seller. In the early

days of this country such faith was often lacking. Great variation existed in the weights and measures

used in different localities, and even, at times, in those used by different individuals in the same locality. The transition from this chaotic situation

to the present uniformity of weights and measures

has resulted from the establishment of accurate,

reliable national standards of length and mass and the enactment of comprehensive weights and measures

statutes. The present highly precise, and extremely stable

national standards for these quantities were not

achieved overnight, or even in a decade. They are

the results of a long period of gradual evolution based

on the dedicated efforts of men who recognized the

growing need for accuracy of measurement. The

story of this development is an interesting one that

is of considerable historical importance, and is told

in the pages that follow.

*The addendum on page 25 covers the period 1963-1976.

In 1905, Louis A. Fischer, then Chief of the Metrology Division of the National Bureau of Standards,

presented a historical treatment of the United States standards of weights and measures before the First Annual Meeting of the Sealers of Weights and Measures of the United States. Although a great deal has

occurred in weights and measures since then, Fischer's account has come to be considered a classic and will

be used freely in the present publication, either

verbatim or with such modifications as seem appropriate.

Fischer's paper was published first in the Proceedings of the First Annual Meeting of the Sealers of Weights and Measures (now the National Conference on Weights and Measures), then published in volume 1 of the Bulletin of the Bureau of Standards,

then as a reprint designated as Scientific Paper No. 17 of the Bureau of Standards, and finally as Miscellaneous Publication No. 64 of the National Bureau

of Standards, an illustrated edition of the address

designated as a memorial to Fischer. Even though

this last publication has long been exhausted, de- mands for it still continue, emphasizing the present

need for an up-to-date historical treatment.

1
I

The place of Louis A. Fischer in metrology has been

so ably described in the Foreword to Miscellaneous

Publication No. 64 that it is reproduced here verbatim.

As a matter of historical record, it is appropriate here to comment

briefly upon Mr. Fischer's career as a metrologist, which began with

his entry, in 1880, into the service of the Office of Standard Weights

and Measures of the Coast and Geodetic Survey. Starting in the workshop, where he was trained in the fabrication of precise standards, he served in all branches of the work up to the making of the most accurate determinations of length and mass, and by 1898 he was in immediate charge of the weights and measures office. When

the Bureau of Standards was established in 1901 that office was made

a part of the new bureau, and in the new organization became the

division of weights and measures of the Bureau of Standards. Mr.

Fischer was at once made chief of this division, a position which

he filled with conspicuous credit from that time continuously until

his death in 1921, except while on duty with the United States Army

during World War I. Throughout the nearly 20 years of his service with the Bureau of Standards, Mr. Fischer was prominently identified with every movement in the United States having to do with the science of metrology

or the supervision of commercial weights and measures. He became

one of the world's foremost experts in the comparison of funda- mental precision standards of length, his work at the International Bureau of Weights and Measures in the recomparison of certain meter bars being especially noteworthy and laying the foundation

for a thorough intercomparison of all national prototypes with

the international standard. Mr. Fischer's services during the World War were of inestimable

value. As technical advisor of the War Department in gauge stand- ardization he was in large measure responsible for the efficient manufacture and inspection of munitions in the many plants throughout

the country, by reason of his thorough practical knowledge of the

subject and the tireless energy he displayed in standardizing and

2. Early History of Weights and

Throughout its early history, the United States Government showed extensive interest in uniform

weights and measures; several efforts were made to secure international agreements in this field. This interest has continued through the years and is stronger

now than ever before. The history of the original Confederation of States and of the constitutional government of the United

States reveals much evidence of the perplexities arising

from the diversity of weights and measures among the

States and of the desirability of a uniform system.

The weights and measures in common use in this country at the time of the American Revolution were

practically all of English origin and were intended to be equivalent to those used in England at that period.

The principal units were the yard, the avoirdupois

pound, the gallon, and the bushel. More or less authentic copies of the English standards of the de- nominations mentioned had been brought over from

time to time and adopted by the different colonies.

coordinating the manufacturing processes and the activities of the hundreds of establishments engaged in this vital work. Nor were his achievements less noteworthy in the more prosaic I field of supervision of the weighing and measuring devices used in

] everyday commercial transactions. Appreciating as he did the fact I that fundamental standards of precision mean but little to the busi- ness life of a community until these standards are translated into I accuracy at the merchants' counters, Mr. Fischer unceasingly de- voted his energies to the task of developing efficient and comprehensive weights and measures supervision on the part of the several States and their local subdivisions, to which agencies the Congress

has left the administration of this important function of govern- ment. As early as 1905 he conceived the idea of an annual confer- I ence of State and local officers charged with the control of weights | and measures in their respective jurisdictions, and in that year called i a meeting of such officers as were then engaged, directly or indirectly,

in this work. This first meeting had a total attendance of but H ( persons, and it was before this small gathering that Mr. Fischer ' delivered the paper which is published herewith, and which has

} since become the classic reference on this subject. From its humble | beginning, however, the Annual Conference on Weights and Meas- I ures has grown until today it is truly national in its scope, and numbers among its members weights and measures officers from all parts

'

of the United States, as well as scores of others, representatives of

business and industry, who are interested in its objects and accom- '| plishments. With the Conference as one of the important mediums ^' through which to work, Mr. Fischer was unceasing in his efforts to fi carry to others his own firm conviction of the tremendous importance a

to every community of adequate weights and measures supervision, y; and to instill into those intrusted with the administration of weights j and measures laws his own high ideals of the responsibility which

^

is theirs and of the service which they should render. As a result, I'

it may truly be said that Louis A. Fischer is the father of what we [ know today as weights and measures control in the United States I

Measures in theUnited States t\

Divergencies in these weights and measures were, j- however, quite common, due no doubt to the fact i- that the system of weights and measures of England ? was not itself well established, and hence the copies ' brought to this country were often adjusted to different f standards. ' That this condition was recognized very early is f made evident by the Articles of Confederation, ratified ' by the colonies in 1781, which contained the following [' clause: "The United States in Congress assembled "

shall also have the sole and exclusive right and power

of regulating the alloy and value of coin struck by f their own authority, or by that of the respective I States—fixing the standard of weights and measures ' throughout the United States— . . .

. " This power <' was transferred to Congress by the Constitution of the ^ United States, effective 1789, in article 1, section 8,

" which reads: "The Congress shall have Power . . .

' To coin Money, regulate the Value thereof, and of

foreign Coin, and fix the Standard of Weights and | Measures."

2
While Congress was not slow to take action in re- gard to coinage, it seems not to have been inclined to come to a decision in regard to weights and measures, though apparently willing enough to consider the

subject. Washington, in his first annual message to Congress, January 1790,' stated that 'uniformity in the currency, weights, and measures of the United

States is an object of great importance, and will, I am

persuaded, be duly attended to." In accordance with

Washington's suggestion, the matter was referred to

a select committee of the House of Representatives

with instructions to prepare a bill, and it was also ordered that the matter be referred to the Secretary of

State to prepare and report to the House a proper plan

for establishing uniformity in the weights and measures.- Jefferson was then Secretary of State, and in response to the above request made a report, in which

he proposed two distinct plans. The first was substantially to "define and render uniform and stable the existing system * * * to reduce the dry and liquid measures to corresponding capacities by establishing

a single gallon of 270 cubic inches and a bushel of

eight gallons, or 2,160 cubic inches * * *." The

second plan was "to reduce every branch to the same

decimal ratio already established for coin, and thus

bring the calculations of the principal affairs of life within the arithmetic of every man who can multiply

and divide plain numbers."^

No action was taken, however, by the House and

in his second message to Congress, on December 8, 1790, Washington again called the attention of that

body to the importance of the subject.* A few days

later the House ordered that ihc Jefferson report,

referred to above, be communicated to the Senate. On March 1, 1791, the Senate committee to which the matter had been referred reported that it would not be

eligible to make a change in the weights and measures,

as a proposition had been made to the French and

British Governments to obtain an international standard.^ This report was accepted and the matter

rested there, although Washington, on October 25,

1791, repeated his former recommendations in his third annual message to Congress, in the following

language : ® A uniformity in the weights and measures of the country is among

the important objects submitted to you by the Constitution and if it can be derived from a standard at once invariable and universal, must be no less honorable to the public councils than conducive to the public convenience.

' Messages and Papers of the Presidents 1, p. 66.

2 Congressional Register 3, p. 106.

' Journal of the H.R,, Childs & Swaine, p. 106.

* Messages and Papers of the Presidents 1, p. 83.

s Jom'nal of the Senate, p. 143; John L. Fenno.

• Messages and Papers of the Presidents 1, p. 108.

A week later the Senate appointed a committee to take into consideration the subject of weights and

measures. The committee reported on the 4th of

April 1792, recommending .lie adoption of the second

plan proposed by Jefferson, which was an entirely

decimal system. Again no definite action was taken.

The matter was considered in a desultory way by

Congress from time to time, but no agreement was

reached notwithstanding that the repeated recom- mendations of Washington were followed by those of

Adams. A sufficient explanation for the disinclina- tion of Congress to act in a matter of such admitted

importance was the difficulty of agreeing upon a plan.

The fifth Congress, second session, in 1799, passed an

act ordering that the surveyor (of each port of the

United States) "shall * * * from time to time, and

particularly on the first Mondays in January and July

in each year, examine and try the weights, measures and other instruments, used in ascertaining the duties on imports, with standards to be provided by each

collector at the public expense for that purpose; and

when disagreements and errors are discovered, he

shall report the same to the collector, and obey and

execute such directions as he may receive for correcting

thereof, agreeably to the standards aforesaid * * *." "

This was the first act passed by Congress in regard

to weights and measures, but, in view of the fact that no standards had ever been adopted, the legislation was not put into operation until about thirty-five years after its passage, when certain standards, which

will be referred to later, were adopted by the Treasury

Department.

After the war of 1812 the question of uniformity in weights and measures was again brought to the

attention of Congress, and in 1819 a committee of the

House of Representatives proposed to adopt absolute

standards conforming to the weights and measures in common use; to obtain through a commission copies

of the yard, the bushel, the wine gallon, and the pound

supposed to conform to those in common use in the

United States; to preserve these standards and to distribute copies of them; to compare the length measure with the length of the second's pendulum

and also with that of an arc of the terrestrial meridian;

to connect them by determining the weight of a certain bulk of distilled water, and to define the

bushel and the gallon by the weight of water which

ihey contain.^ No further record of the report is found, and it may be assumed that no action upon

it was taken. The Senate had, by a resolution adopted

March 3, 1817—two years prior to the above report

' statutes at Large 1, p. 643.

* Executive Doc. No. 73, 30th Cong., 1st sess., Senate.

3
This weight was legalized by act of Congress, May 19, 1828, as the "standard troy pound of the mint" to regulate the coinage. It was displaced as the standard for the coinage by act of Congress, March 4, 1911, when the "standard troy pound of the Bureau of Standards" was adopted for this purpose

requested the Secretary of State to prepare and report

a "statement" relative to the regulations and standards for weights and measures in the several States and relative to the proceedings in foreign countries

for establishing uniformity in weights and measures,

' together with such propositions relative thereto as

| might be proper to adopt in the United States. John Quincy Adams was at that time Secretary of

State, and four years later, on February 22, 1821, he

submitted an elaborate report to the House of Representatives in which he reviewed the history of weights

\ and measures in England, on the continent of Europe, ] and in the United States. He considered in detail I the history of the metric system, and analyzed its merits and deficiencies. That system, a logical deci- mal system of weights and measures based upon

measurements of a quadrant of the earth's meridian

and the mass of a measured quantity of water, was

one of the new ideas resulting from the French Revolution. The basic unit of the metric system as originally

conceived was to be a meter, a unit equal to one ten- millionth part of a quadrant of the earth's meridian

as measured from the North Pole to the equator. A

cube having sides of length equal to one-tenth of a meter was to be the unit of capacity, the liter, and

the mass of a volume of pure water equal to a cube of

one-tenth of a meter at the temperature of melting i ice was to be the unit of mass, the kilogram. 'V The necessary measurements and the construction ,i of standards was entrusted to committees ("commis- j sions") composed of members of the Institute of j;- France ("Institut National des Sciences et des Arts")

i and of deputies from other countries. The first undertaking was that of making extensive geodetic \„ and astronomical measurements along a meridian j,; from Dunkirk to Barcelona using the toise, an old ' French unit of length equal roughly to 6 U.S. feet

| and by modern measurements found to be equal to i, 1.949 090 meters, as the unit of length and computing

the length of a quadrant of that meridian. From . these results there was constructed a one-meter bar of |, platinum, the length of which was intended to be ;| the one ten-millionth part of the length of the meridional quadrant. This bar, having its length define J

|, by the distance between its two ends, became the "Meter of the Archives."

Twelve iron copies of this meter bar were con- , structed by a committee under the special direction of ,•

J. G. Tralles, the deputy from the Helvetic Republic. , Two of these copies were assigned to Tralles, who

then gave one, known in this country as the "Comj mittee Meter," to his friend Ferdinand R. Hassler

4
who was selected by President Jefferson to be in charge of the Survey of the coast of the United States. As will be seen, this bar later played an important

part in the weights and measures of this country.

After the Adams report had reviewed the status of

weights and measures at home and abroad, including an analysis of the advantages and disadvantages of

the metric system, it made a number of recommendations, the final ones being "1. To fix the standard,

with the partial uniformity of which it is susceptible,

for the present, excluding all innovation. 2. To

consult with foreign nations, for the future and

ultimate establishment of universal and permanent

uniformity."

As before. Congress took no action, probably

because the situation at that time was extremely

complicated. Neither the metric system in France

nor the system in common use in England was well

established. In France, the law making the metric

system compulsory had been repealed, and the metric

system was in use side by side with the ancient

weights and measures, thus producing endless confusion. In England the situation was not much

better; the ale gallon of 282 cubic inches and the wine

gallon of 231 cubic inches were both in use until 1824, when the new imperial gallon, containing

10 pounds of water, and of a capacity of about 277)2

cubic inches, was adopted, together with the bushel

of 8 gallons. Neither of these measures was in use

in this country, and hence the United States could

not at that time adopt either the system in use in England or the one in France without introducing

radical changes in the weights and measures already

in use, nor was there at that time any positive as- surance that either the English or the metric system

would be permanent.

While Congress had been considering the matter,

most of the States had, independently of one another,

secured and adopted standards. Most of the standards thus adopted were brought from England; nevertheless, standards of the same denomination differe

' widely among themselves, thus perpetuating confusion in the commerce between the States. Though confusion in commercial transactions

might be tolerated, uncertainty in regard to the

coinage could not be tolerated, and on May 19, 1828,

a certain troy pound was adopted as the standard for coinage by Congress in an "Act to continue the

Mint at the City of Philadelphia, and for other

purposes." Section 2 of this act reads as follows:

And be it further enacted, That, for the purpose of securing a due

conformity in weight of the coins of the United States * * * the

brass troy pound weight procured by the minister of the United

States at London, in the year one thousand eight hundred and

twenty-seven, for the use of the mint, and now in the custody of the Mint at Philadelphia, shall be the standard troy pound of the Mint of the United States, conformably to which the coinage

thereof shall be regulated. The troy pound thus adopted had been procured in 1827 by Albert Gallatin, United States minister at London, and brought to this country by special messenger, who delivered it to the director of the

Mint at Philadelphia. The weight was of brass and

an "exact" copy of the imperial troy pound of Great

Britain, according to the statement of Captain Kater,

who made the comparison between the two standards.

The casket and accompanying packages were retained

under seal until President Adams visited Philadelphia

and verified Gallatin's seal and the other facts in regard to its authenticity.

This ceremony took place on October 12, 1827, and

the full certificate of President Adams in regard to the seal, which he readily recognized, and to the

whole transaction and consequent accuracy of the

weight was added to the vouchers in the case. He

declared, in conclusion, his belief that the brass weight then exhibited was the identical pound copy

of the imperial standard troy pound of Great Britain.

These facts were communicated to Congress through

Committee on the Mint and resulted in the passage of

the act cited above. This act was not modified until 83 years later, in 1911. A report of Samuel Moore on

the original troy pound of the Mint, giving many

interesting details, is reproduced in appendix 2. While the act of Congress of 1828 only made this pound the standard for coinage, it virtually became

the fundamental standard of the United States from

which the avoirdupois pound in common use was

derived.

On May 29, 1830, two years after the mint pound

had been legalized for coinage, the Senate passed a resolution directing the Secretary of the Treasury to

cause a comparison of the weights and measures in use at the principal customhouses to be made, and to report to the Senate at its next session. Steps were promptly taken by the Treasury Department to comply with the resolution of the Senate. The preliminary report ofF. R. Hassler, Superintendent of the Coast Survey, to whom the investigation

had been intrusted, was transmitted to the Senate on March 3, 1831; ® a more complete report followed in June 1832. As was anticipated, large discrepancies were found

to exist among the weights and measures in use at the

different ports, some being too small and others too

8 See H.R. Doc. No. 299, 22d Cong., 1st sess.

5
large, but the average value of the various denominations agreed fairly well with the weights and measures

in use in Great Britain at the time of the American

Revolution,

Without waiting for authority from Congress the Treasury Department took immediate steps to correct the situation by having constructed, under Hassler's

direction, the necessary weights and measures for the

customs service. The divergencies among the

weights and measures in use in the customs service were directly opposed to the spirit of the Constitution, which requires that all duties, imposts, and

excises shall be uniform throughout the United States,^" and the Secretary of the Treasury felt fully authorized

in taking steps to secure uniformity when discrepancies were found.

3. Units and Standards

Before weights and measures could be constructed,

however, it was necessary for the Treasury Department

to decide uoon certain units and to adopt standards,

that is, the material representatives of these units. A clear understanding of the difference between

"units" and "standards" will aid the reader in the

sections that follow.

A unit is a determinate quantity (that is, one

established by definition) in terms of which values,

quantities, amounts, or magnitudes are expressed.

Being fixed by definition, a unit is itself independent

of physical conditions—as, for example, temperature

even though it may be defined in relation to some

object that is affected by such conditions. Thus a particular unit of capacity may be defined as a volume

of a specified number of cubic inches; the United

States gallon is so defined—as a unit of 231 cubic

inches. Or again, a particular unit of length may be

defined as a distance corresponding to the interval between certain engraved lines on a certain metal bar

when measured under specified conditions, including

those of the support and the temperature of the bar;

until October I960 the meter unit was so defined in relation to the international meter bar. A standard is the physical embodiment of a unit. In general a standard is not independent of physical

conditions and is a true embodiment of the unit only

under specified conditions. Thus a 1-gallon metal

standard will have a capacity of 1 gallon only when

the standard is at a certain temperature; at any other

temperature the capacity of the standard will have

been increased or decreased as a result of the expansion

or contraction of the metal caused by the temperature

change. Or again, a length standard having a nominal

value of one yard will have an actual value of one

yard only when at one particular temperature and

when supported in a certain manner; a lowering of its temperature will cause the standard to shorten, a

raising of its temperature will cause it to lengthen,

and a change of the manner in which it is supported

may introduce a change in its length.

When a unit is defined in terms of a standard, the

latter acquires a fundamental character; the International Prototype Meter was such a standard until the meter unit was redefined in I960. Standards are classified into groups, according to their character, the

order of their accuracy, and the order of their legal or other importance. Thus there are, for example,

international and national

'

' prototypes,

'

' State

'

' refer- ence" standards, "laboratory working" standards,

"field" standards, and various "classes" of standards

established largely on the basis of design and accuracy.

4. Early United States Standards

The units finally adopted by the Treasury Department in 1832 were the yard of 36 inches, the avoirdupois pound of 7,000 grains, the gallon of 231 cubic

inches, and the bushel of 2,150.42 cubic inches. The

standard yard adopted was the 36 inches comprised

between the 27th and the 63d inches of a certain brass

bar, commonly designated as an 82-inch bar, prepared

for the Coast Survey by Troaghton of London.

Hassler had brought this bar to the United States in 1815, after he had been detained in Europe for several years by the War of 1812. The 36-inch space referred to was supposed to be identical with the English

standard at 62 °F, although it had never been directly

compared with that standard.

It is evident from Hassler's reports that he regarded

the English yard as the real standard of length of the

United States and the Troughton scale merely as a copy whose length should be corrected if it was subsequently found to differ from the English yard; and

this view was taken by others who subsequently had

charge of our standards, as will be shown later on. The avoirdupois pound adopted by Hassler as the

standard for the Treasury Department was derived

from the troy pound of the Mint according to the

equivalent, 1 avoirdupois pound equals pounds

troy. This was the accepted relation in this country

as well as in England; hence both the troy and avoirn Article I, sec 8, clause 1.

6
Under the terms of an act passed in 1838 the Secretary of the Treasury was directed to furnish balances to the States. As furnished, a complete set of these balances comprised a 50-pound balance, a medium balance of about 10 pounds capacity, and a small balance of about

1-pound capacity. (See note 11, p 8.) These balances are on display at the National Bureau of Standards.

Standards of length, mass, and capacity furnished to the States under the joint resolution of Congress of June 14, 1836.

In the illustration the half-bushel measure is at the upper left, the liquid measures—^1 gallon to pint—at upper right; slicker plates are

in position atop each of these capacity measures. The 13 weights at the left are troy standards. Avoirdupois standards are above and to

I

the right of the troy weights. In the foreground are the yard and matrix. 7

j
dupois pounds adopted were in practical accord

with the similar standards of Great Britain. The units of capacity, namely, the wine gallon of

231 cubic inches and the Winchester bushel of 2,150.42

cubic inches, were adopted because, as intimated, they

represented more closely than any other English

standards the average of the capacity measures in use

in the United States at the date of Hassler's investi- gation. The wine gallon was introduced as a wine

measure into England in 1707, during the reign of

Queen Anne, but it was abolished in 1824, when the new imperial gallon, containing 10-pounds of water, was made the standard. This last statement applies

also to the bushel of 2,] 50.42 cubic inches. This

bushel is the earliest English capacity measure of

which we have any record, a copy of it made by order

of Henry VII being still in existence. But this bushel

had also been abolished in England, it having been

superseded by the bushel of 8 imperial gallons.

Therefore neither the gallon nor the bushel adopted

by the United States Treasury Department was in accord with the legal capacity standards of England,

but they were smaller by about 17 percent and 3 percent, respectively, and these differences exist at the

present time. Not only did they differ from the new

standards in Great Britain, but they also differed from

the discarded English standards from which they were

derived for the reason that Hassler selected the temperature of the maximum density of water as the temperature at which the United States measures were

standard, whereas their English prototypes were

standard at 62 °F. The numerical value in degrees

Fahrenheit of the temperature at which water has its maximum density was determined by Hassler to be

39.83 °F; later and more precise determinations have

shown this to be 39.2 °F. Such, then, were the fundamental standards adopted

by the Treasury Department on Hassler's recommendation; and the weights and measures for the customs

service were constructed to conform to these. The

construction of the weights and measures for this purpose was pushed with almost feverish haste, and

so well satisfied was Congress with the progress made

that the following resolution was passed and approved

June 14, 1836:

Resolved by the Senate and House of Representatives of the United States

of America in Congress assembled. That the Secretary of the Treasury be, and he hereby is, directed to cause a complete set of all weights and

measures adopted as standards and now either made or in progress

of manufacture for the use of the several custom-houses, and for other purposes, to be delivered to the governor of each State in the Union, or such person as he may appoint, for the use of the States,

respectively, to the end that a uniform standard of weights and

measures may be established throughout the United States.

While the resolution does not specifically adopt the

standards described above, its practical effect was to make them the standards for the United States, inas- much as the weights and measures distributed to the

States in accordance with the act were in almost every

case adopted by the State legislatures soon after their

receipt.

By 1838 the weights for the States were reported

finished, and, during the following year, the weights

for the customhouses were completed and delivered."

The resolution of 1836 was supplemented by Congress by the act of July 7, 1838, an act having the

original purpose "to provide for the support of the

Military Academy of the United States for the year 1838." One of several amendments to this act, however, reads as follows

:

That the Secretary of the Treasury cause to be made, under the

superintendence of Mr. Hassler, one standard balance for each State, and that when completed he cause them to be delivered to the re- spective Governors for the use of the respective States.

It is interesting that under this authority balances

in three capacities instead of one were built for the

States, a large (capacity 50 pounds), a medium

(capacity about 10 pounds), and a small (capacity

1 pound). A commentary on this departure from the

specific terms of the statute is found in House Docu- I ment No. 159, 28th Congress, 2d Session; this doc- \ ument comprises a report dated February 26, 1845,

by A. D. Bache, Hassler's successor as Superintendent

of Weights and Measures, on the progress made in the construction of standard weights, measures,

j and balances during the year 1844. Appended to

[ Bache's report, as appendix A thereto, is a special I report, dated January 4, 1844, made to the Secretary

j of the Treasury by Edward Hassler, a son of F. R.

| Hassler, who had served for some years as his father's

assistant in the construction of weights, measures,

j and balances. In this special report Edward Hassler 1 quotes that paragraph of the 1838 Act authorizing

j the furnishing to each State of "one standard bal- ance," and then goes on to say: , The spirit of the above law is, that the States be furnished with I means by which they will be enabled to determine any question 1 that may arise, with such a degree of nicety as to be as valuable

for all practical purposes as if absolutely exact. This object cannot be secured by any single balance; consequently ^

arises the necessity of seeking the best means of accomplishing the

desired object. Experience has proved that it cannot be secured , with sufficient accuracy by less thau three balances. ; Consequently, I considered myself justified in carrying ont the '

spirit, and securing to the country the important and so-much-

| needed object of the law. \ ***** i

11 H.R. Doc. 159, 28th Cong., 2d sess.
It is not clear from the records now available that

each State received three balances, one of each

capacity, but it is known that this was the case in some States, and it is presumed that the normal

distribution was on the basis of three balances per

State. By 1850 practically all the States admitted to the

Union had been supplied with complete sets of weights

and measures, and, in addition, sets were presented

to England, France, Japan, and Siam. As new

States were admitted they were also supplied with

sets of standards, the last of these sets being supplied

to North Dakota in 1893. Two special sets of

standards have since been prepared. One was pre- sented to the State of Alaska in 1959 and the other

presented to the State of Hawaii in 1960. A list of the weights and measures comprising one

of the original State sets is given below.

First. A set of standard weights composed of one each of the following:

Avoirdupois weights

founds ounces ounce ounce 50 8 0.05 0. 0005

25 4 0.04 0. 0004 20 2 0.03 0. 0003

10 1 0.02 0. 0002

5

'2 0.5 0.01 0. 0001 4 0.4 0.005

3 0.3 0.004 2 0.2 0.003

1 0.1 0.002

0.001

weights

pound ounces ounce ounce

1 10 0.5 0.005

6 0.4 0.004

5 0.3 0.003

4 0.2 0.002

3 0.1 0.001

2 0.05 0. 0005

1 0.04 0. 0004

0.03 0. 0003 0.02 0. 0002

0.01 0. 0001

(The avoirdupois and troy weights 0.05 ounce and

smaller were made of silver wire.)

Second. A standard brass yard measure, with

Matrix.

Third. A set of liquid capacity measures, consisting

" The denominations of some of the weights were changed in sets supplied

after 1857. Instead of decimal parts of the ounce, weights of the following denominations were furnished: J-a ounce, 1.4 ounce, ounce, and J-le ounce;

50, 25, 10, 5, 4, 3, 2, 1, 0.05, 0.04, 0.03, 0.02, and 0.01 grains.

of one of each of the following, with its groundglass cover.

1 gallon

y2 gallon

1 liquid quart

1 pint

M pint

Fourth. A brass standard half-bushel with a ground glass cover. In order to carry out the provisions of the resolution

of 1836 and the act of 1838 the Office of Weights and

Measures had been established under the direction of

the Superintendent of the Coast Survey. All the

standards adopted at the beginning of the work, and

subsequently, were in the charge of this Office, with

the exception of the troy pound of the Mint, which

remained at Philadelphia.

In October 1834, the British imperial yard and troy

pound made in 1758, of which the Troughton scale and the mint pound were supposed to be exact copies, were destroyed by the burning of the Houses of Parlia- ment. When the new imperial standards to replace

them were completed in 1855 two copies of the yard

and one copy of the avoirdupois pound were presented

to the United States, arriving in this country in 1856. One of these bars, namely, bronze yard No. 11, was

very soon after compared with the Troughton scale,

the result showing that the accepted 36 inches of the

Troughton scale was 0.00087 inch longer than the

British imperial yard.^^ The second bar received from

England was subsequently compared with the Troughton scale and fully corroborated the result obtained

from the comparison with bronze No. 11. The new

yards, and especially bronze No. 11, were far superior

to the Troughton scale as standards of length, and

consequently they were accepted by the Office of

Weights and Measures as the standards of the United

States, and all comparisons were afterwards referred to the imperial yard through these two standards.

They were twice taken to England and recompared

with the imperial yard, once in 1876 and again in 1888. The avoirdupois pound presented with the two

yards was also compared with the United States avoirdupois pound derived from the mint pound, the

result showing a very satisfactory agreement. The

advent of the new pound did not, therefore, disturb

the position of the troy pound of the Mint, or of the

avoirdupois pound derived from it. There is a refer- ence concerning this comparison of the pounds made

by Alexander D. Bache, Superintendent of Weights

and Measures, in a report dated December 30, 1856 to

13 See Report of the Secretary of the Treasury on the construction and

distribution of weights and measur es in 1857. S. Ex. Doc. No. 27, 34th Cong., 3d sess. 9
the Treasury Department (34th Congress, 3d Session, Senate Executive Document No. 27, p. 18):

The copy of the British standard commercial pound was compared

with the American standard commercial pound—the weight used

being that made by Mr. Hassler from the troy pound in the United

States mint, and marked with a star (commonly designated as the

star pound').

In the standards vault of the National Bureau of

Standards there is preserved a 1-pound avoirdupois

brass knob weight marked on the top surface of the

knob with a star. Although positive identification

is not possible, it seems not unreasonable to assume

that this weight is the standard referred to in the

Fischer and Bache texts. (See illustration p. 22.)

At present there is no United States national prototype avoirdupois pound constituting the ultimate

national reference standard for avoirdupois standards

of lower order. Laboratory sets of avoirdupois

standards are in use, but these are derived from the

national prototype kilogram.

5. Use of Metric System Officially Permitted

The next and perhaps the most important legislation

enacted by Congress was the act of 1866 legalizing the metric system of weights and measures in the United

States. The act, which was passed July 28, 1866, reads as follows

:

Be it enacted by the Senate and House of Representatives of the United

States of America in Congress assembled. That from and after the passage

of this act it shall be lawful throughout the United States of America

to employ the weights and measures of the metric system; and no

contract or dealing, or pleading in any court, shall be deemed invalid

or liable to objection because the weights or measures expressed or

referred to therein are weights or measures of the metric system. SEC. 2. And be it further enacted. That the tables in the schedule

hereto annexed shall be recognized in the construction of contracts, and in all legal proceedings, as establishing, in terms of the weights and measures now in use in the United States, the equivalents of the weights and measures expressed therein in terms of the metric system; and said tables may be lawfully used for computing, determining, and expressing in customary weights and measures the weights and

measures of the metric system.

(See tables on facing page.) While the above act was being considered, Congress

also considered a resolution authorizing the Secretary of the Treasury to furnish the States with metric weights

and measures. Strange to say, this resolution, which

logically should follow, was approved one day

before the act legalizing the use of the metric system.

It was a joint resolution and read as follows:

Be it resolved by the Senate and House of Representatives of the United

States of America in Congress assembled. That the Secretary of the

Treasury be, and he is hereby, authorized and directed to furnish

to each State, to be delivered to the governor thereof, one set of

standard weights and measures of the metric system for the use of

the States, respectively. The work of making and adjusting these standards

fell naturally upon the OfHce of Weights and Measures, and the first matter to be resolved was the choosing of the reference standards. The practice

followed by those countries that had adopted the

metric system of accepting the meter and the kilo- gram of the Archives of France as fundamental

standards was followed by the United States. The

question then was mainly one of securing authentic

copies of these standards. Fortunately the Office of

Weights and Measures had several copies of both

standards of more or less authenticity on hand,

but without hesitation the iron bar known as the

" Committee Meter" and a platinum kilogram, known

as the "Arago Kilogram," were selected. The committee meter has already been mentioned

as being one of the copies of the meter of the Archives,

and thus a standard of considerable importance in the

metric system. As stated before, this bar is made of

iron, with a cross section of 9 by 29 mm, and its length

is defined by the end surfaces, which are remarkably

plane when one considers the age in which the bars were made. The bar bears the stamp of the committee, namely, a small ellipse. Three quadrants

of the ellipse are shaded and the fourth one clear, except for the number 10,000,000, which indicates the number of meters in a meridian quadrant of the

earth. In Hassler's report on the construction of

the meters ^* it is stated, on the authority of Tralles,

that all the meters agreed with the true meter within

one-millionth part of the toise.^^ This is equivalent to about two millionths of a meter, the toise being equal to approximately 1.95 meters. When Hassler came to the United States in 1805

he brought with him the committee meter, which

he soon after presented to the American Philosophical

Society of Philadelphia, Pa. Shortly after, when he was put in charge of the survey of the coast, the meter was placed at his disposal by the Philosophical i

Society, and he made it the standard of length for that work. Until 1890 all base measurements of the! Coast Survey were referred to this meter. Thus it

| was natural that this bar should be selected as the^ standard to which the State meters should conform,

j " II R. Doc. No. 299, 22d Cong., 1st sess., pp. 75, 76.

15 The toise was the French standard of length prior to the adoption of the

j meter, and all the geodetic measurements upon which the meter was based

| were made with the toise. Its length is 1.949+meters.

| 18 Special Publication No. 4, U.S. Coast and Geodetic Survey.

^

i

10

I
MEASURES OF LENGTH

Metric dcnominationa and values EiQuivaients id denoniinations in use

myriameter * .

.

10 000 meters

1 000 meters n fowl rrtil^ nr \ 7fln f^^r anH in inrhpc 328 feet and 1 inch. 393.7 inches. meter 1 meter 39. 37 inches.

3. 937 inches. 0.3937 inch. 0.0394 inch.

MEASURES OF CAPACITY

Metric denominations and values Equivalents in denominations in use

Names Number

of liters Cubic measure Dry measure Liquid or wine

measure

kiloliter or stere *, hectoliter dekaliter

liter deciliter

centiliter

milliliter

1 000

100

10

1 Mo

Moo

Mooo

1 cubic meter Mo of a cubic meter . . . 10 cubic decimeters . .

.

1 cubic decimeter Mo of a cubic decimeter

10 cubic centimeters .

.

1 cubic centimeter ....

1.308 cubic yards

2 bushels and 3.33 pecks

9.08 quarts 0.908 quart 6.1022 cubic inches. . .

.

0.6102 cubic inch

0.061 cubic inch

264.17 gallons. 26.417 gallons. 2.6417 gallons. 1.0367 quarts. 0.843 gill. 0.338 fluid ounce.

0.27 fluid dram.

MEASURES OF SURFACE

Metric denominations and values Equivalents in denominations in use

2.471 acres. 119.6 square yards.

1, 530 square inches.

WEIGHTS

Metric denominations and values Equivalents in denominations in use

Names Number of grams Weight of what quantity of water at maximum density Avoirdupois weight

milIier*or tonneau * quintal*

myriagram*

kilogram or kilo*.

.

hectogram

dekagram tram

ecigram

centigram

milligram

1 000 000

100 000

10 000

1 000

100

10

1 Mo

Moo Mooo

1 cubic meter

1 hectoliter 10 liters

1 liter

1 deciliter 10 cubic centimeters . .

.

1 cubic centimeter Mo of a cubic centimeter 10 cubic millimeters . .

.

1 cubic millimeter

2204.6 pounds.

220.46 pounds.

22.046 pounds.

2.2046 pounds.

3.3274 ounces. 0.3527 ounce.

13.432 grains. 1.3432 grains. 0.1543 grain. 0.0154 grain.

*Ed. Note: These terms are obsolete.

11
Metric standards of length, mass, and capacity, furnished to the States under the joint resolution of Congress of July

27, 1866.

In the illustration the liter (litre) and the dekaliter (decalitre) are at the upper left and center, each with a slicker plate in position. The weights are centrally positioned. In the foreground are two meter bars, the upper one a line standard and the lower

one an end standard.

International Standard of Mass

Calibrated at National Bureau of Standards

INTERNATIOflAL KILOGRAM T

KILOGRAM 20 T

NBS LABORATORY STANDARDS

(Metric and United States Customary)

United States National Standard of Mass Cali- brated at International Bureau of Weights and Measures

Calibrated in State Laboratories

STATE REFERENCE STANDARDS T

STATE LABORATORY STANDARDS

Calibrated at National Bureau of Standards

STATE FIELD STANDARDS CITY AND COUNTY STANDARDS

REGULATORY CONTROLS

12

Progression of standards.
The Arago kilogram was procured in 1821 by

Gallatin while minister of the United States to France and was sent to this country, together with a plati- num meter. The certificate of Arago, the celebrated

physicist, which accompanied these standards, states that the kilogram differs from the original kilogram

of the Archives by less than 1 mg. The weight is a platinum cylinder with flat bases, the edges being

slightly rounded. The height and diameter are nearly equal, being approximately 39.5 mm each. There is no stamp or distinguishing mark of any kind,

except near the center of one base there is a faint lathe

or tool mark of circular form, thus: O The weight

is contained in a square mahogany box, on the cover

of which is a circular silver plate bearing the inscription "Kilogramme compare pour son Poids a I'Etalon Prototype des Archives de France, et verifie par M.

Arago. Fortin fecit." (Kilogram compared for its weight with the prototype standard of the Archives

of France, and verified by Mr. Arago. Made by

Fortin.) No particulars of Arago's comparison with

the kilogram of the Archives were furnished, and

consequently it is not known what means he used in making his comparison nor whether he reduced his weighings to vacuo. It was not until 1879 that the

Arago kilogram was compared with other standards

of recognized authority. It is true that it was compared between 1852 and 1873 vvith two kilograms in the possession of the Ofhce of Weights and Measures,

but as both of these weights were of brass and of

unknown density, no great reliance could be attached

to the results. In 1879, however, it was taken to England and there compared with the British plati- num kilogram in the custody of the Standards Office. This comparison indicated that the Arago kilogram was 4.25 mg light, but this result could not be considered conclusive, on account of certain assumptions

made in the reduction to vacuo and also in regard to the correction to the British kilogram.

In 1884 the weight was taken from the Standards

Office in London, where it had been since 1879, to the

International Bureau of Weights and Measures at Paris and there compared with two auxiliary kilograms whose values in terms of the kilogram of the

Archives were known with the greatest accuracy. The result obtained from the comparison confirmed

that previously obtained from the comparison with

the British kilogram, the result giving

Arago kilogram = 1,000 g —4.63 mg.

As the weights supplied to the States were to be

made of brass, it was more convenient to compare them

with a brass standard, and in order to do this two

secondary brass standards were carefully compared

between the years 1873^1876 with the A rago kilogram

and afterwards used in all the work of adjustment and

verification. One of the kilograms, known as the

Silbermann kilogram, was presented to the United

States by France in 1852, together with a number of

other weights and measures. The other kilogram

used was one made in the Office of Weights and

Measures and was identical in form and material with

the kilograms subsequently furnished to the States. As the unit of capacity in the metric system is defined as the volume of the mass of 1 kilogram of

pure water at the temperature of maximum density,

the most convenient way to adjust such measures, and

in fact all capacity measures, is by weighing the

water they contain. The only two material standards that need to be considered, therefore, in connection with the metric weights and measures fur- nished to the States in accordance with the act of 1866

are the committee meter and the Arago kilogram

described above.

By the end of 1880 practically all the States had

been supplied with sets of metric weights and measures consisting of the following denominations:

Length measures . ,

Capacity measures.

Weights

One brass line meter. One steel end meter.

J One liter made of brass. [One dekaliter made of brass. One 10-kilogram made of brass. One kilogram made of brass. One ;^-kilogram made of brass. One gram made of brass. One set of small silver weights

, from 4 decigrams to 1 milligram.

6. International Standards of Weights and Measures

It is necessary at this point to go back a few years and give an account of the establishment of the Inter- national Bureau of Weights and Measures, since the

present fundamental standards of length and mass for practically the whole civilized world result from the

establishment of that institution. In response to an invitation of the French Government, the following countries sent representatives to

a conference held in Paris on August 8, 1870, to consider the advisability of constructing new metric

standards: Austria, Colombia, Ecuador, France, Great

Britain, Greece, Italy, Norway, Peru, Portugal,

Russia, Spain, Switzerland, Turkey, and the United

States of America, 15 countries in all. This confer13
cnce was of short duration, on account of the war

then raging between France and Germany.

A second conference was held two years later, at which 26 countries, including the United States, were

represented. At this conference it was decided that new meters and new kilograms should be constructed

to conform with the original standards of the Archives,

and a permanent committee was appointed to carry out this decision. The preparation of the new standards had advanced so far by 1875 that the permanent

committee appointed by the conference of 1872

requested the French Government to call a diplomatic

conference at Paris to consider whether permanent means and appliances for the final verification of the new meters and kilograms should be provided, or whether the work should be regarded as a temporary

operation.

In compliance with this request a conference was

held in March 1875, at which 20 countries were

represented, the United States as usual being included.

On May 20, 1875, 17 of the 20 countries represented

signed a document known as the " Metric Convention"

or the "Treaty of the Meter." This provided for the establishment and maintenance of a permanent

International Bureau of Weights and Measures to be

situated near Paris and to be under the control of an

international committee elected by the General

Conference on Weights and Measures.

In addition to the original primary work of verifying the new metric standards the International Bureau was charged with certain duties, the following being

the most important:

(1) The custody and preservation, when completed,

of the international prototypes and auxiliary instru- ments.

(2) The future periodic comparison of the several national standards with the international prototypes.

(3) The comparison of metric standards with

standards of other countries. The expenses of the bureau were to be defrayed by

contributions of the contracting governments, the

amount for each country depending upon the population and upon the extent to which the metric system was in use in the particular country.

After ratification by the U.S. Senate and the ex- change of ratifications at Paris, the Metric Convention was "proclaimed" by Rutjherford B. Hayes,

President of the United States, on September 27, 1878. The twenty countries represented at the diplomatic

conference at which the treaty was prepared and

signed were Argentina, Austria-Hungary, Belgium,

Brazil, Denmark, France, Germany, Great Britain,

Greece, Italy, the Netherlands, Peru, Portugal, Russia,

Spain, Sweden-Norway, Switzerland, Turkey, the

United States of America, and Venezuela. Three of | these countries did not sign the convention at that time—Great Britain, Greece, and the Netherlands. , Under the terms of the Convention an International

Conference of Weights and Measures was established, i to meet once every six years and to comprise official delegates designated by each Power signatory to the

[ Convention . The International Committee elected by

this Conference meets every two years. | A Convention amending the 1875 Convention was

signed at Sevres, France, on October 6, 1921; after the

customary preliminaries this was proclaimed by Presi- i dent Calvin Coolidge on October 27, 1923. Among ' othct amendments made, the new Convention broadened the scope of the work of the International Bureau, \ enlarged the International Committee from 14 to 18

j members, revised the method of calculating the contributions to be assessed against signatory countries

for the support of the Bureau, and modified the

procedure for access to the standards vault at the

International Bureau. { The number of powers adhering to the Metric

j Convention—and thus supporting the International

Bureau—has increased to 44. Argentina, Australia,

Austria, Belgium, Brazil, Bulgaria, Cameroon, Canada, Chile, Czechoslovakia, Denmark, Dominican ' Republic, Egypt, Federal Republic of Germany,

Finland, France, German Democratic Republic,

Hungary, India, Indonesia, Iran, Ireland, Italy, , Japan, Korea, Mexico, The Netherlands, Norway,

Pakistan, Poland, Portugal, Rumania, Spain, South

Africa, Sweden, Switzerland, Thailand, Turkey,

USSR, United Kingdom, USA, Uruguay, Venezuela,

Yugoslavia.

The International Committee has had as members,

| j at one time or another, many of the world's leading i mctrologists. The United States has been represented !i on the Committee by J. E. Hilgard (1875-1887;, I B. A. Gould (1887-1896), A. A. Michelson (1897-

1904), S. W. Stratton (1905-1931), A. E. Kennelly

(1933-1939), E. C. Crittenden (1946-1954), A. V.

Astin (1954-1969), L. M. Branscomb (1969-1972)

and E. Ambler (1972- ). I

I The International Bureau of Weights and Measures j

is situated in the town of Sevres, France, near the

[ Sevres end of the Park of St. Cloud, which extends i between the towns of St. Cloud and Sevres. The ! « plot of ground was ceded by France to become inter- s national territory. The main office building, used ^

also for the library and for the home of the Director,

| was originally a royal dwelling known as the Pavilion de Breteuil. The present official address of

14
The International Bureau of Weights

and Measures,

Sevres, France.

the bureau is Pavilion de Breteuil, Sevres (Seine-etOise), France. The construction of the meters and kilograms had

been entrusted to a special committee which carried out its tasks meticulously and with great scientific thoughtfulness. These international and national

standards were designated as "prototypes," a term

that is confusing in the minds of many people. Notwithstanding the dictionary definition of "prototype" as the original, model, or pattern after which

something is copied, the term in metrological

usage signifies that which is first in status or chief in rank or importance, a usage that dates back at least to 1875. Thus the expression "International Prototype Kilogram" is used to mean the kilogram standard that ranks highest as an international standard,

that provides the most authentic value in the world

for the kilogram mass, and not necessarily as the

pattern for the construction of other kilogram standards. The expression "United States National Pro- totype Kilograms No. 20 and 4" is used to mean the

particular kilogram standards, identified as "No. 20"

and "No. 4," respectively, which standards rank

highest in this country.

The international and national prototype meter

bars, constructed in accordance with the terms of the

Convention of the Meter of 1875, are of like design;

the cross section is designed to provide maximum

rigidity in a bar of reasonably small dimensions and

mass, and to reduce to a minimum the effects of any

slight bending that may take place when a bar is in normal use. This cross section is a modified X known

as the "Tresca section" in honor of the French

scientist, Henri Tresca, who proposed it. The overall dimensions of the cross section of the prototype meter

bars are 20 x 20 millimeters.

In a bar of Tresca cross section, the upper surface of

the central rib lies in the plane of the neutral axis of

the bar, the plane in which any variations in the

length of the bar that may be caused by slight de- formation of the bar are reduced to the practicable

minimum.

The international and national prototypes are approximately 1020 millimeters in overall length.

As originally constructed (some bars have been

regraduated in recent years), near each end of a bar, on the upper surface of the central rib, is a small,

elliptical, polished area, and on this area are engraved

two groups of parallel lines, the first comprising three

transverse lines and the second two longitudinal lines. The central lines of each of the two transverse groups

are the essential defining lines of the bar, the auxiliary

lines being positioned at one-half millimeter distances on either side. (These auxiliary lines were intended

for such purposes as calibrating the micrometer

microscopes of length comparators.) The lines of

each transverse group are crossed by the lines of a longitudinal group, these latter lines being 0.2 milli- meter apart and somewhat more than 1 millimeter in length; the longitudinal lines serve to identify that

small portion of each defining line that is to be utilized when the bar is used. Also engraved on each bar is

its identifying number.

As for the international and national kilograms,

they are in the form of right circular cylinders of

equal diameter and height—approximately 39 milli- meters—with slightly rounded edges. Engraved on

each is its identifying number.

Thirty-one meter bars and 40 kilograms were

constructed under the supervision of the International Bureau. The work of construction and calibration was completed by 1889; and in September of that year

15
the first General Conference on Weights and Measures was held in Paris, and this work was approved at this meeting.

The meter and kilogram that agreed most closely

with the meter and kilogram of the Archives were

declared to be the international meter and the inter- national kilogram. These two standards, with

certain other meters and kilograms, were deposited

in a subterranean vault under one of the buildings of the International Bureau, where they are only accessible when three independent officials with different keys are present. The other standards were distrib- uted by lot to the various governments contributing

to the support of the International Bureau. Those

falling to the United States were meters Nos. 21 and

27 and kilograms Nos. 4 and 20.

7. The Men

On April 5, 1893, T. C. Mendenhall, then Superintendent of Weights and Measures, with the approval

of the Secretary of the Treasury, decided that the

international meter and kilogram would in the future be regarded as the fundamental standards of length

and mass in the United States, both for metric and

customary weights and measures. This decision,

which has come to be known as the "Mendenhall

Order," was first published as Bulletin No. 26 of the Coast and Geodetic Survey, approved for publication

April 5, 1893, under the title, " Fundamental Standards

of Length and Mass"; it was republished in 1894 under

the same title, as appendix No. 6—Report for 1893

of the Coast and Geodetic Survey, "to give it a more

permanent form." In appendix No. 6 there was

included as an addendum to the text of Bulletin No. 26

a section headed "Tables for Converting Customary

and Metric Weights and Measures," comprising some text, five customary-to-metric conversion tables,

and five metric-to-customary conversion tables.

Meter No. 27 and kilogram No. 20 were brought

under seal to this country by George Davidson, of the Coast and Geodetic Survey. On January 2, 1890, the

packing cases containing these standards were opened

at the White House and the standards were accepted

by President Harrison, who certified that they were

received in good condition and that he confidently

believed that they were the standards referred to in the reports. These reports, relating to the standards

in question, had been submitted by B. A. Gould,

United States delegate to the International Conference on Weights and Measures, and by Davidson. The

other two standards were received the following

July and were deposited in the Office of Weights and

Measures, where those accepted as national standards

by the President had already been taken.

lenhall Order

As a matter of interest and record, the full text of

appendix No. 6 of the Report for 1893 of the Coast

and Geodetic Survey, with the exception of an

editorial footnote and the ten conversion tables, is reproduced as appendix 3 of this publication.

The Mendenhall Order initiated a departure from

the previous policy of attempting to maintain our

standards of length and mass to be identical with

those of Great Britain, and thereafter there was a small difference between the British and the United

States yards, a difference which may have been negligible in 1893 but which became of real importance as the British Imperial Yard bar gradually changed in length and as the requirements for greater accuracy

in measurements increased. As has been seen, when the United States yard was

first adopted upon Hassler's recommendation in 1832,

it was defined as a particular interval on the Troughton

bar, through which it was related to the British yard

standard. The intention was to fix the United States yard as equal to the British yard.

When the "Imperial" system of weights and

measures was established by the British in 1824, the Imperial Yard was defined in terms of a specific yard

standard and a particular bar was legalized as the

Imperial standard. In 1834, that bar was so damaged

in the burning of the Houses of Parliament that

replacement was necessary; a new bar was constructed,

and in 1855 this bar was legalized as the new Imperial

Standard Yard. In the course of the years this bar

proved to be insufficiently stable in length and was

found to be shortening by measurable amounts.

Upon the establishment of the Buroau of Standards on July 1, 1901, all standards and other property in possession of the Olllce of Weights and

Measures passed under the control of the Buieau.

16
For a time, efforts were made by United States authorities to maintain equivalence between the United States and British yards. Such efforts were

abandoned, however, in 1893, when the Mendenhall

Order (see appendix 3, p. 26) defined the United States yard in terms of the International Prototype Meter. The difference between the United States and the

British yards, prior to the 1959 actions of both governments in recognizing the new International Yard

Csee appendix 5, p- 28), reached a maximum value

in the order of 0.000 13 inch, the United States yard

being the longer.

The case of the pound was slightly different as will

be seen from the record of the values assigned to it with respect to the kilogram.

The United States law of 1866 that made the use of

the metric system permissive, carries the relation,

1 kilogram =2.2046 avoirdupois pounds, an equation now believed to have been intended as sufficiently accurate for commercial purposes but not as a precise definition of the relationship between basic units. This value resulted from a rounding off of the results of an 1844 comparison made in England between the

British pound and the Kilogram of the Archives

which gave the relation, 1 pound =0.453 592 65 kilo- gram; this relation was used in Great Britain and in the United States for years. Expressed reciprocally,

this relation becomes, approximately, 1 kilogram =

2.204 621 61 pounds.

In the Coast and Geodetic Survey Report for 1893

that contained the Mendenhall Order, (see appendix

3, p. 26), the kilogram-avoirdupois pound relation- ships are variously stated as follows:

1

1 pound avoirdupois

2.2046

1 2.20462

kg

kg

= 1 kilogramme =453.592 427 7 grammes

1 pound avoirdupois

2.204 622 34 pounds

avoirdupois

1 avoirdupois pound

A comparison made in 1883 between the British

Imperial Standard Pound and the International Prototype Kilogram resulted in the relation 1 Imperial

Pound =0.453 592 427 7 Kilogram; this relation was

accepted in both Great Britain and the United States, but uniformity between the two countries ended in 1889 when Great Britain ofhcially adopted a roundedoff value, making the relation, 1 Imperial Pound =

0.453 592 43 Kilogram. From its founding in 1901

until July 1, 1959, the National Bureau of Standards

recognized and used the relation 1 pound avoirdupois =0.453 592 427 7 kilogram.

This uncertainty as to the precise values of the

units of length and mass in common use, the yard and

the pound respectively, was caused by inadequacies

of the standards representing them. The bronze

yard No. 11, which was an exact copy of the British

imperial yard both in form and material, had shown

changes when compared with the imperial yard in 1876 and 1888 which could not reasonably be said

to be entirely due to changes in No. 11. Suspicion

as to the constancy of the length of the British stand- ard was therefore aroused. Neither the troy pound

of the mint nor the copies of the imperial yard in the

possession of the Ofhce of Weights and Measures were

satisfactory standards. The mint pound is made in two pieces, the knob being screwed into the body;

hence its density can not be determined by weighing

in water on account of danger of leakage. Moreover,

it is made of brass not plated, and therefore liable to alteration by oxidation.

On the other hand, the new meters and kilograms

represented the most advanced ideas of standards, and

it therefore seemed that greater stability in our weights and measures as well as higher accuracy would be secured by accepting the international meter and kilogram as fundamental standards. Time proved the wisdom of this action, and therefore when the National Bureau of Standards was

established in July 1901, it fully accepted the decision

made by the Office of Weights and Measures in 1893

to adopt the meter and kilogram as fundamental

standards. The National Bureau of Standards was established

in response to the requests of scientists, technologists,

and industrialists that a governmental agency be

founded to develop standards, carry out researches

basic to standards, and calibrate standards and devices. The Office of Weights and Measures had carried out some of this work in its limited field, and the increas- ing use of electricity was making the need of a central standardizing authority rather critical. Similar needs were also felt in other fields of science and industry.

Institutions of the type envisioned had already been

formed in Great Britain and Germany and the Office of Weights and Measures was deemed to be a suitable nucleus on which to build in this country. Fortunately, Congress was favorably impressed with the

idea and on March 3, 1901 it passed an act providing

that "The Office of Standard Weights and Measures

shall hereafter be known as the National Bureau of

Standards" and setting forth the functions of the new

Bureau. These functions were considerably expanded

in an amendment passed in 1950. 17
,„7:::z:7r«. • "7t:_„.w

A^-- """^^ .,.1 /7,a/ ''c

In- J"'" ^ ^'^ ''^'^ , ^. i.,„nx->- tiinrminq thai tI.eM TK-ototype. -v— „„ ...

V, , ,„,..c .-..^

„, — ^ -'777:; ^ ... 77;:^:

leUt-ye to he "^"^ £^

^—7 i/zy -
o'clock P^M.M of TUThM^sd^y January 2^-

^itrtessed lyJ the me ur,^. undersvgrved,, who

^^riaturcs hereto, in. tesUmorvy thereof.

1890, was

^^"6 uiUiched. Oie.i

^^^^

, ^^^^^

Army,

"'"P'rinu.uUnt. us.Ki,,^,

^^^^^

^ -""^ '^"•"^ Z'w o;^

^ofessof of PI,

Certificate in relation to the receipt of

the national prototype metric standards

of length and mass.

The original of this certificate is preserved

in the standards vault of the National Bureau

of Standards.

Certificate in relation to the ceremony of breaking the

seals of Meter No. 27 and Kilogram No. 20.

The original of this certificate is preserved in the standards vault of the National Bureau of Standards. It will be observed that the last signature on this certificate is that of Louis A. Fischer, who signed as Adjuster, Office of Weights

and Measures.

19
1

in expanding the work in weights and measures

into a national standards bureau, the work in the field of weights and measures had more opportunities for growth. Mr. Louis A. Fischer, Chief of the Division

of Weights and Measures from the organization of the

National Bureau of Standards in 1901 until his death

in 1921, probably was the first man in the United

States to undertake the promotion of weights and

measures supervision on a national basis. In 1902,

Mr. Fischer directed scattered inspections of weighing

and measuring devices and transactions involving

quantities in several of the larger cities in the State of New York. The purpose of these visits was to deter- mine what amount of protection the buying public was receiving against short weight and short measure

in purchases. As a result of this investigation, as well as the increasing number of complaints being

received in Washington, staff members of the National

Bureau of Standards decided in 1904 to call a meeting

of weights and measures officials and other officers of the State governments to discuss ways and means of affording to the public adequate supervision over weights and measures in everyday transactions. This meeting was held in Washington in 1905, and,

although invitations went to all States, the meeting was attended by only eleven persons, representing

eight States, the District of Columbia, and the

National Bureau of Standards. As it turned out, this was the first National Conference on Weights and

Measures, and was the inauguration of meetings that have been held annually with exceptions due to war or other national emergency. Interest, attendance, and

participation in the Conferences, as well as the

influence of the Conference, have increased steadily.

The registered attendance at the 47th meeting, held in

8. ReFinement oF Vol ues When the National Bureau of Standards began its work in 1901 the principal units of weights and measures in the U.S. customary system were defined as follows

:

, 3600

1 y^'^'i = 3^ meter

1 pound = 0.453 592 427 7 kg

1 gallon =^231 cubic inches

1 bushel = 2 150.42 cubic inches

These definitions remained unchanged for 58 years, and the last two are still the official values. The precision requirements in length measurements

increased greatly during these years, and the differ- ences between the U.S. inch and the British inch

became especially important in gage-block standard20

Washington during June 1962, was 420. Out of thv National Conference on Weights and Measures has come the basis for uniformity of weights and measures law and enforcement activities. The delegates to the first Conference and to all subsequent meetings have had as their principal aim

the application of uniform and satisfactory standards

of measurement to everyday commercial transactions. The need for uniformity of State weights and measures legislation was one of the principal reasons for the first national meeting of weights and measures

officials and was considered at that time. As the re- sult of a resolution of the second meeting, a Model

State Law on Weights and Measures was composed.

In the year 1911, after detailed and extensive discussions, the Sixth National Conference adopted, with a few minor changes and additions, a Model Law that

had been drafted at the National Bureau of Standards.

Since that time this document has been subject to continued study and revisions, additions, and deletions have been made as needed. Thus was made

available to the States a model upon which individual

State legislation could be patterned.

Supplemental to the Model Law are codes of specifications, tolerances, and regulations for commercial

weighing and measuring devices which receive

especially critical attention, because many of the

States officially adopt these requirements by reference or citation with cumulative provision, resulting in

their being given legal status upon adoption by the

Conference and publication by the National Bureau of

Standards. Manufacturers of equipment are guided

in their engineering designs, and essentially all weights

and measures inspectors aline their procedures,

according to the Conference codes.

for the Yard and Pound

ization. The difference between the U.S. pound and

the British pound was also rather annoying. As a result of many years of preliminary discussion, the

directors of the national standards laboratories of

Australia, Canada, New Zealand, South Africa, the

United Kingdom, and the United States entered into

agreement, effective July 1, 1959, whereby uniformity was established for use in the scientific and technical

fields. The equivalents 1 yard =0.9144 meter (whence

1 inch =25-4 millimeters) and 1 avoirdupois pound =

0.453 592 37 kilogram (whence 1 grain= 0.064 798 91 gram and 1 avoirdupois ounce=28.349 523 125 grams) were adopted for each of these national laboratories.

It will be noted from the U.S. announcement (see

appendix 5, p. 28) that these same equivalents will

also be used in this country in trade.
9. Wavelength DeFinition of the Meter

It is obvious that exactness in units must have its basis in standards that are as permanent and exact as possible. Ever since 1890 when Michelson made his famous measurements of the wavelength of light in terms of the meter, metrologists have been giving

consideration to the idea of defining the meter in terms of the wavelength of light. Researches by

many scientists have been carried out to find a wavelength generally acceptable for use as an ultimate

standard and to specify the conditions of its use. Finally, on October 14, I960, the 11th General Conference on Weights and Measures adopted a new

definition of the meter as 1 650 763.73 wavelengths of

the orange-red radiation of krypton 86, or more

specifically in scientific terms, as 1 650 763-73 wavelengths in vacuum of the radiation corresponding to the transition between the levels Ipio and 5'^5 of the

krypton 86 atom. The National Bureau of Standards has adopted this definition (see appendix 6, p. 30), and thus it will not be necessary for the United States prototype meter No. 27 to be taken to the International Bureau for comparison as has been done in the past—in 1903,'*

1922, 1956, and 1957—where its relation to the inter- national prototype meter has been found to remain

essentially constant. The international prototype meter will continue to be maintained at the International Bureau and comparison of national prototypes with it will continue

to be made. Likewise, the national prototype meters

at the National Bureau of Standards will continue to be used for many precise calibrations of length standards. An interesting sidelight on the change in the defini- tion of the yard is found in measurements made just

prior to April 1893 indicating that

1 U.S. yard =0.914 399 80 meter

or

1 meter=39.370 09 U.S. inches

a relation which differs by only 2 parts in 9 million

from the value finally adopted in 1959. The observers,

however, had in mind the value given in the 1866 law

and noted that the value 1 meter=39.3700 inches "is

evidently sufficiently precise for geodetic purposes and

has the advantage of being convenient and easily

remembered . '

Although some thought has been given to a possible

definition of the kilogram in terms of some invariable

physical phenomenon instead of in terms of a material

standard, no satisfactory solution has yet been dis- covered. The U.S. national prototype kilogram No.

20 was compared with international standards in 1937

and 1948 with excellent results.

10. Other DeFinitions oFUnits

Three other changes in the weights and measures

field have occurred during the past 60 years. First, there was the change made in 1911 in the law defining the troy pound. At that time the words "the standard troy pound of the Bureau of Standards of the United States" were substituted for the description

of the troy pound of the Mint.

Next, in 1913, the international metric carat was

defined as the equivalent of 200 milligrams, thereby

eliminating the use of a number of unofficial or semiofficial carats. Third, in 1954, the Secretary of Commerce and the

Secretary of Defense agreed to use the international

nautical mile in their respective departments instead

of the older U.S. nautical mile. (See appendix 4, p. 28.) The practical effect of this action was that

the use of the U.S. nautical mile has virtually dis- appeared.

11. Current and Historical Standards oF Length and Mass at the National Bureau

oF Standards

This history of weights and measures in the United

States concludes with a descriptive list of some of the more important standards of length and mass either

" In 1903 there was an apparent shortening of approximately 0.4nm in meter

bar No. 27, but subsequent observations showed that there had been no

shortening of this bar, but rather a lengthening of the two laboratory meter

bars used in the comparisons and small errors in the coefficients of thermal

expansion of the bars involved.

(a) currently in use or (b) not in current use but of

historical interest, that are in the custody of the

National Bureau of Standards.

Standards Currently in Use

Mefer27. —National prototype meter, a line standard

made of platinum-iridium, Tresca cross section (modified X), received by the United States from the Inter21

Formerly the national prototype standards of length and mass were kept in a cabinet at one

side of the standards vault, as here illustrated. This view shows Louis A. Fischer, first Chief of the Division of Weights and Measures of the Bureau and, as such, custodian of the national prototype meter and kilogram.

23
national Bureau of Weights and Measures in 1889. This meter was the United States national reference standard for all length measurements from 1893 to 1960, and in I960 became the primary bar, secondary

only to the basic value of the meter in terms of the

wavelength of Kr^*^ light. Merer 21. —National prototype meter of same material and design as Meter 27, received by the United

States from the International Bureau of Weights and

Measures in 1890. Meter 12. —A platinum-iridium line-standard meter, Tresca cross section (modified X), made of the "Alloy

of 1874," and received by the United States from the

International Bureau of Weights and Measures in 1889.

It was regraduated in 1948 by the National Bureau of

Standards in terms of the wavelength of red cadmium

light. Meter 4. —A platinum-iridium graduated line-stand- ard meter, Tresca cross section (modified X), made of

the "Alloy of 1874," and purchased by the United

States in 1907. It is graduated to 1-millimeter divi- sions for the entire 1-meter interval and is of special

utility in making comparisons of intervals of less than

1 meter. Kilogram 20. —National prototype kilogram, a mass

standard made of platinum-iridium in the form of a cylinder of equal diameter and height, received by

the United States from the International Bureau of Weights and Measures in 1889. It has been the United States national reference standard for all mass

measurements since 1893. Kilogram 4. —National prototype kilogram of same

material and design as Kilogram 20, received by the United States from the International Bureau of

Weights and Measures in 1890. It is secondary to Kilogra\tn 20.

Standards of Historical Interest

Committee Meter.—An iron end standard of length, 9 millimeters by 29 millimeters in cross section. This

bar is one of a group of similar bars made in France in 1799 by the committee that made the Meter of the Archives, whence its designation in the United States

as the "Committee Meter." This particular bar was

presented by Tralles, the Swiss member of the committee, to his friend F. R. Hassler; Hassler, in turn

sold it to a member of the American Philosophical

Society in Philadelphia, who deposited it with the

Society. Later the bar was obtained from the Society

by Hassler for the use of the U.S. Coast and Geodetic

Survey, where it was used as the standard for scientific work in the United States from 1807 to 1893. 24

Arago Meter. —A platinum line standard of length, 5 | millimeters by 25 millimeters in cross section. The i bar was procured from France in 1821 by Albert Galla-

'

tin. Minister of the United States to France; it derives

j its designation from the name of the eminent French

physicist who certified the length of its graduated

'

interval. It appears that this bar has received

essentially no use as a standard in the United States. Troughton Scale. —A graduated line standard of

| length, commonly designated as an 82-inch bar, made j by Troughton of London in 1814 and procured in 1815 I for the United States by F. R. Hassler. The bar, Yi

I inch by 2}^ inches in cross section, is made of brass ( with an inlaid silver strip on which Ko-inch gradu- i ations are engraved. The interval between the 27th

j and 63d inch graduations was selected by Hassler in ; 1832 to define the United States standard yard, and the

^ Troughton Scale retained its position as the primary

reference yard standard of the United States until f about 1857.

'

Bronze Yard No. 11. —A bronze line standard of '

length, 1 inch by 1 inch in cross section, having an

J overall length of 38 inches. Near each end of the |. bar is a cylindrical well with an inset gold plug, the upper surface of the plug being }> inch below the top

surface of the bar. The 1-yard defining lines are engraved on the gold plugs. This bar is of the same

material and form as the British Imperial Yard legal- ized in 1855, and was presented to the United States by Great Britain in 1856. It was used as the standard ' yard of the United States from about 1857 to 1893. I Low Moor Iron Yard No. 57. —An iron line standard | of length, similar in design and construction to Bronze

[ Yard No. 11. It was presented to the United States f by Great Britain in 1856, and was in use in the United | States as a standard until 1893, being regarded as

| secondary in importance to Bronze Yard No. 11. ji Committee Kilogra/n. —A brass standard of mass, |) cylindrical, with knob. This standard is one of a i group of similar standards made in France in 1799 by ) the committee that made the Kilogram of the Ar-

| chives, whence its designation in the United States I as the "Committee Kilogram." This standard was ^ presented by Tralles, the Swiss member of the com- ; mittee, to his friend F. R. Hassler, Hassler, in turn, sold it to a member of the American Philosophical

Society in Philadelphia, who deposited it with f; the Society. Later, the standard was obtained ' from the Society by Hassler, who made use of it in ij connection with his standards work for the U.S. ^ Coast and Geodetic Survey. ' Arago Kilogram. —A platinum kilogram made in

\ France by Fortin and certified by Arago. It was pro- I
cured in France in 1821 for the United States by

Albert Gallatin, Minister of the United States to France. Prior to 1890, this kilogram was used as one of the standards of the United States.

Silbertnann Kilogram.—A gilded brass standard of mass, cylindrical, with knob. This standard was

presented to the United States by France in 1852,

and became a secondary standard in the Office of

Standard Weights and Measures of the U.S. Coast

and Geodetic Survey, used particularly in connection

with the adjustment and verification of metric standards supplied to the States. Grave.—A cylindrical knob weight, one of six made

in 1793 by the French Temporary Commission on

Weights and Measures as representing the unit of

weight of a proposed system of weights and measures.

Originally called the "grave", in 1795 the unit was

renamed the "kilogram." This weight is from a set of weights brought to the United States in 1793, and

it appears that the set came into the possession of one Andrew Ellicott, at one time an assistant to Major

Pierre Charles L'Enfant who planned the city of Washington. The subsequent history of this set of weights

is somewhat obscure, but it seems probable that the

set remained in pri^^ate hands, probably within the

Ellicott family, until 1952, when what remained of the

set was donated to the National Bureau of Standards

by its owner at that time. Dr. A. Ellicott Douglass of

the University of Arizona.

"Star" Avoirdupois Pound.—A cylindrical knob

weight marked on the top surface of the knob with a

star. Although positive identification cannot be

made, it appears not unreasonable to assume that this standard is the actual weight "made by Mr. Hassler

from the troy pound in the United States mint, and

marked with a star (commonly designated as the star pound)" as referred to by A. D. Bache, Superintendent of Weights and Measures, in his report of

December 30, 1856, to the Secretary of the Treasury.

Imperial Avoirdupois Pound, Copy No. 5. —A goldplated brass standard of mass, cylindrical in form

with a circumferential groove (instead of a knob) to

facilitate handling. This standard was received in 1856 as a gift from Great Britain to the United States.

It was used as the standard representing the United

States***** avoirdupois pound from 1856 to 1893.

12. Addendum (The period I963-(975)

Three Laws that have been enacted since 1963, the

original date of publication of Miscellaneous Publication 247, are worthy of note:

Public Law 89-755, the Fair Packaging and Labeling

Act. This Act, signed into law on November 3, 1966,

became effective July 1, 1967. Section 2 of this Act

reads as follows

:

"informed consumers are essential to the fair and efficient functioning of a free market economy. Packages and their labels should enable consumers to obtain accurate information as to the quantity of the contents and should facilitate value comparisons.

Therefore, it is hereby declared to be the policy of the Congress

to assist consumers and manufacturers in reaching these goals in the marketing of consumer goods."

The authority to promul'^ate regulations under the Act was vested in the Secretary of Health, Education,

and Welfare and the Federal Trade Commission. The

Secretary of Commerce was authorized to furnish to

state officers and agencies information and assistance

to promote to the greatest practicable extent uniformity in State and Federal regulation of the labeling

of consumer commodities.

Recognizing the need for compatibility with the

Federal Act, the Committee on Laws and Regulations

of the 53rd National Conference on Weights and

Measures in 1968 amended the Model State Packaging

and Labeling Regulation (first adopted in 1952) to

parallel regulations adopted by Federal agencies

under the Fair Packaging and Labeling Act. The

process of amending and revising this model regulation is a continuing one, in order to keep it current with practices in the packaging field and make it compatible with appropriate Federal regulations.

Federal and State mandatory provisions require that

all packages shall declare the identity of the com- modity and the name and place of business of the

manufacturer, packer or distributor; and the net quantity of contents (in terms of weight, measure or numerical count) shall be separately and accurately

stated in a uniform location upon the principal dis- play panel. In 1974, the model regulation was amended

to provide for uniformity in the use of metric symbols

and is currently being revised to fully accommodate

the conversion to the metric system.

25
Public Law 93-380, "the Education Amendments

of 1974," enacted August 21, 1974 includes a Section

(403. (aXl)) which states that "It is the policy of the

United States to encourage educational agencies and

institutions to prepare students to use the metric

system of measurement with ease and facility as a part

of the regular education program." The Office of

Education, Department of Health, Education, and

Welfare is responsible for implementing this policy.

Public Law 94-168, the "Metric Conversion Act of

1975," enacted December 23, 1975 declares that "the

policy of the United States shall be to coordinate and

plan the increasing use of the metric system in the

United States and to establish a United States Metric

Board to coordinate the voluntary conversion to the

metric system." PL 94-168 thus recognizes that increasing use of the metric system as of 1975 is an

actuality in the United States and places responsibility

for coordinating this increasing use in a U.S. Metric

Board appointed by the President. Both PL 93-380 and PL 94-168 provide that "metric

system of measurement" means the International

System of Units (commonly referred to as SI) as established by the General Conference on Weights and

Measures in 1960 and as interpreted or modified for the United States by the Secretary of Commerce.

On behalf of the Secretary of Commerce the National

Bureau of Standards has implemented this responsibility by having published a Federal Register Notice

dated June 19, 1975 which is reproduced as Appendix 7.

26

Two Federal Register Notices related to our customary system of weights and measures have been published since 1963. A Federal Register Notice of July 27, 1968 (see

appendix 8), issued in response to a request of the

House Committee on Science and Astronautics lists the weights and measures used in normal commerce

and relates them to the standards developed in accordance with existing law.

A Federal Register Notice of February 3, 1975 (see

appendix 9) supplements the July 27, 1968, Notice;

it explains the difference between the survey mile and

international mile on the one hand and the survey

foot and the international foot on the other. It is of

interest to note that the international foot and mile

are exactly 0.999 998 as long as the survey foot and

mile, respectively. Although the term statute mile

(5280 feet) can be interpreted to be either the survey

mile or the international mile, in the United States, the U.S. statute mile remains the same as the U.S. survey mile. Starting in 1965 with the enactment of Public Law

89-164 the Congress, over a ten-year period, appropriated a total of 1.8 million dollars to the National

Bureau of Standards for the specific purpose of supplying standards of weight and measure to the States. These funds have been used to supply sets of

customary and metric standards of weight (mass),

length, and volume, as well as precision balances

to practically all of the 50 States and also to the

District of Columbia, the Commonwealth of Puerto

Rico, and the Virgin Islands.

i

f till,
Appendix 1. Bibliosraphy

The first of the following principal sources consulted

in the preparation of this publication was used very

j extensively. It is therefore pieced at the head of the

i list; the others are listed alphabetically.

FISCHER, Louis A., History of the Standard Weights

and Measures of the United States, NBS Miscellane- ous Publication 64; BACHE, Alexander D., Report on the Construction

and Distribution of Weights and Measures, S. Ex. Doc. No. 27, 34th Congress, 3d Session;

j BIGOURDAN, Guillaume, Le Systeme Metrique des

' Poids et Mesures;

I CHANEY, Henry J., Our Weights and Measures;

Appendix 2. Report on th

Reproduced below is the text of an appendix to the

report of the Committee of the Franklin Institute on

Weights and Measures comprising a report of Dr. Samuel Moore, Director of the United States Mint,

dated October 1, 1833, dealing with the original troy

pound of the Mint. This report was printed in the

Journal of the Franklin Institute of the State of

I Pennsylvania in the issue of May 1834 (Vol. XIII,

New Series, No. 5), p. 302-3. APPENDIX TO THE REPORT OF THE COMMITTEE OF THE

FRANKLIN INSTITUTE ON WEIGHTS AND MEASURES

Report of Dr. Samuel Moore on the authtntuatien of the Troy Pound in

possession of the Mint of the United States To the oommtttee of the Franklin Institute charged with the subject of Weights and Measures Mint ol the United States, October 1, 1833. The standard troy pound of the mint is a copy, executed with great

care, of the British parliamentary troy pound of 1758, recognised and designated in the year 1824 as the imperial troy pound of Great

Britain. It was procured at my request, in 1827, through the attention and influence of Mr. Gallatin, Minister of the United States at London. By the friendly offices of Mr. Davies Gilbert, Vice Presi- dent of the Royal Society, the standard troy pound in the care of the Clerk of the House of G>mmons, was, on the application of Mr.

Gallatin to the Speaker of the House, committed to the charge of

I dpt. Kater, for the purpose of effecting at his own house an adjustI ment of the copy to the original. The standard weight is of brass, the original being of that material. It was made by Mr. Bate, who had constructed all the standard British weights, and the comparison with the original was made

by a very delicate beam constructed by Robinson, the same artist who had constructed the beam with which Capt. Kater compared

the standard weights above mentioned with the original standard

troy pound. The weight was enclosed in a neat casket carefully enveloped

under seal of the American legation at London, and committed by

CHISHOLM, Henry W., On the Science of Weighing

and Measuring and Standards of Measure and

Weight;

GUILLAUME, Charles E., La Creation du Bureau

International des Poids et Mesures et son Oeuvre;

HASSLER, Ferdinand R., Comparison of Weights and

Measures, H. R. Doc. 299, 22d Congress, 1st Session;

BOARD OF TRADE, GREAT BRITAIN, Reports on

their Proceedings and Business under the Weights

and Measures Act 1878; COMITE INTERNATIONAL DES POIDS ET MESURES, Proces Verbaux des Seances; CONFERENCES GENERATES DES POIDS ET

MESURES, Comptes Rendus des Seances.

: Troy Pound of the Mint

Mr. Gallatin himself to the hands of Mr. Cucheval, a public messenger, bearing despatches from the legation to the United States, by whom it was delivered into my hands, accompanied by a packet

containing ample certificates from dpt. Kater and Mr. Gallatin,

tcstifvin^ to the accuracy of the weight in question.

The casket and accompanying package were retained under seal, waiting the return of Mr. Adams, President of the U.S., from his family residence to Washington, in order that the seal of Mr. Gallatin, and the various facts of chief moment, in regard to the authenti- cation of the weight, might be verified, on his authority. They

were accordingly opened in the presence of Mr. Adams, in Philadelphia, on the 12th of October, 1827, and his full certificate in regard

to the seal, which he readily recognised, and to the circumstances

generally, giving assurance of the fidelity of the whole transaction, and the consequent accuracy of the weight, has been added to the vouchers in the case; he declaring, in conclusion, his entire belief, that the brass weight then exhibited was the identical copy of the imperial standard troy pound of Great Britain, intended and referred to in the aforesaid certificates. The above facts having been communicated to Congress through

the committee on the mint, the troy pound thus certified was specif- ically declared by law to be "the standard troy p>ound of the mint

of the United States, according to which the coinage thereof shall be regulated." Sec section 2nd of the act of May 19, 1827, respecting the mint, a copy of which is hereto annexed. This is the specific pound weight, assumed as the standard unit of

the system of weights reported to the Senate of the United States, under a resolution of that body of 29th May, 1830—see a communication from Mr. Ingham, Secretary of the Treasury, made to the Senate March 3d, 1831 ; also the report of Mr. Hassler on the subject, 27th January, 1832, pages 10 and 25; and a communication to the Senate from Mr. M'Lane, Secretary of the Treasury, accompanying

this report, dated 20th June, 1832. It has been constantly in my

possession, and is preserved with the utmost care.

Very respectfully, gentlemen. Your obedient servant, Samuel Moore,

Director United States Mint.27
Appendix 3. The Mendenhall Order of

April 5, 1893

This order was published as appendix 6 of the

Report for 1893 of the Coast and Geodetic Survey.

FUNDAMENTAL STANDARDS OF LENGTH AND MASS

While the Constitution of the United States authorizes Congress

to "fix the standard of weights and measures," this power has never been definitely exercised, and but little legislation has been enacted upon the subject. Washington regarded the matter of sufficient importance to justify a special reference to it in his first annual message

to Congress Qanuary, 1790), and Jefferson, while Secretary of State, prepared a report, at the request of the House of Representatives,

in which he proposed Quly, 1790) "to reduce every branch to the decimal ratio already established for coins, and thus bring the cal- culation of the principal affairs of life within the arithmetic of every man who can multiply and divide

. ' ' The consideration of the subject being again urged by Washington, a committee of Congress reported

in favor ofJefferson's plan, but no legislation followed. In the meantime the executive branch of the Government found it necessary to

ftrocure standards for use in the collection of revenue and other operations in which weights and measures were required, and the Troughton 82-inch brass scale was obtained for the Coast and Geodetic

Survey in 1814, a platinum kilogramme and metre, by Gallatin, in 1821, and a troy pound from London in 1827, also by Gallatin. In 1828 the latter was, by act of Congress, made the standard of mass for the Mint of the United States, and, although totally unfit for such

purpose, it has since remained the standard for coinage purposes.

In 1830 the Secretary of the Treasury was directed to cause a comparison to be made of the standards of weight and measure used at the principal custom-houses, as a result of which large discrepancies were disclosed in the weights and measures in use. The Treasury Department, being obliged to execute the constitutional provision that all duties, imposts, and excises shall be uniform throughout the United States, adopted the Troughton scale at the standard of length; the avoirdupois pound, to be derived from the troy pound of the Mint, as the unit of mass. At the same time the Department adopted

the wine gallon of 231 cubic inches for liquid measure and the Winchester bushel of 2130.42 cubic inches for dry measure. In 1836 the

Secretary of the Treasury was authorized to cause a complete set of

all weights and measures adopted as standards by the Department for the use of custom-houses and for other purposes to be delivered to the governor of each State in the Union for the use of the States, respectively, the object being to encourage uniformity of weights and

measures throughout the Union. At this time several States had

adopted standards differing from those used in the Treasury Depart- ment, but after a time these were rejected, and finally nearly all the

States formally adopted, by act of legislature, the standards which

had been put in their hands by the National Government. Thus a good degree of uniformity was secured, although Congress had not

adopted a standard of mass or of length, other than for coinage

purposes, as already described. The next and in many respects the most important legislation upon

the subject was the act of July 28, 1866, making the use of the metric system lawful throughout the United States and defining the weights and measures in common use in terms of the units of this system . This was the first f/tntral legislation upon the subject, and the metric sys- tem was thus the first, and thus far the only, system made generally

legal throughout the country.

In 1873 an international metric convention was agreed upon by

seventeen Governments, including the United States, at which it was

undertaken to establish and maintain at common expense a permanent international bureau of weights and measures, the first object

of which should be the preparation of a new international standard metre and a new international standard kilogramme, copies of which

should be made for distribution among the contributing Governments. Since the organization of the Bureau, the United States has

regularly contributed to its support, and in 1889 the copies of the new international prototypes were ready for distribution. This was

effected by lot, and the United States received metres Nos. 21 and 27 and kilogrammes Nos. 4 and 20. The metres and kilogrammes are made from the same material, which is an alloy of platinum with 10

per cent of iridium. On January 2, 1890, the seals which had been placed on metre No.

27 and kilogramme No. 20 at the International Bureau of Weights

and Measures, near Paris, were broken in the Cabinet room of the Executive Mansion by the President of the United States in the pres- ence of the Secretary of State and the Secretary of the Treasury, together with a number of invited guests. They were thus adopted

as the national prototype metre and kilogramme. The Troughton scale, which in the early part of the century had

been tentatively adopted as a standard of length, has long been

recognized as quite unsuitable for such use, owing to its faulty construction and the inferiority of its graduation. For many years, in

| standardizing length measures, recourse to copies of the imperial j yard of Great Britain had been necessary, and to the copies of the

( metre of the archives in the office of weights and measures. The

standard of mass originally selected was likewise unfit for use for ! similar reasons, and had been practically ignored. The recent receipt of the very accurate copies of the International Metric Standards, which are constructed in accord with the most

advanced conceptions of modem metrology, enables comparisons to be made directly with those standards, as the equations of the

national prototypes are accurately known. It has teemed, therefore, that greater stability in weights and measures, as well as much

'

higher accuracy in their comparison, can be secured by accepting i the international prototypes as the fundamental standards of length

|! and mass. It was doubtless the intention of Congress that this should be done when the international metric convention was

entered into in 1873; otherwise there would be nothing gained from

the annual contributions to its support which the Government hat

constantly made. Such action will also have the great advantage

of putting us in direct relation in our weights and measures with

all civilized nations, most of which have adopted the metric system

for exclusive use. The practical effect upon our customary weights ' and measures is, of course, nothing. The most careful study of the !! relation of the yard and the metre has failed thus far to show that

the relation as defined by Congress in the act of 1866 it in error. |i The pound as there defined, in in relation to the kilogramme, differs ' from the imperial pound of Great Britain by not more than one

part in one hundred thoutand, an error, if it be to called, which

utterly vanishes in comparison with the allowances in all ordinary

transactions. Only the most refined scientific research will demand

a closer approximation, and in scientific work the kilogramme itself

is now universally used, both in this country and in England.*

'Note.—Reference to the act of 1866 results in the establishment of the

following:

3600 ': 1 yard = metre. | i 3937 1 1

1 1 pound avoirdupois « kg. * 2 * 2046

^ A more precise value of the English pound avoirdupois is—^— kg., differ- 1^ 2-20462

1^ Ing from the above by about one part Inone hundred thousand, but the equa- | tioD established by law is sufficiently accurate for all ordinary conversions. ^ As already stated, in work of high precision the klloKramme is now all but ' universally used and no conversion is required. '

28
In view of these facts, and the absence of any material normal

standards of customary weights and measures, the Office of Weights

and Measures, with the app»roval of the Secretary of the Treasury,

will in the future regard the International Prototype Metre and Kilogramme as fundamental standards, and the customary units

the yard and the pound—will be derived therefrom in accordance with the Act of July 28, 1866. Indeed, this course has been practi- cally forced upon this Office for several years, but it is considered

desirable to make this formal announcement for the information of

all interested in the science of metrology or in measurements of

precision. T. C. Mendenhaix,

Suptrintendtnt of Standard Weights and Measures. Approved

:

J. G. Caklulb,

Stcrttary «f tbt Trtasury. Apeu, 5, 1893.

(United States Coast and Geodetic Survey.—Office of Standard Weights and Measures—T. C. Mendenhall, Superintendent.]

TABLES FOR CONVERTING CUSTOMARY AND METRIC

WEIGHTS AND MEASURES.

Ofhcb of Standard Wbiohti and Measubbs,

Washingttm, D.C., Manb 21, 1894.

The yard in use in the United States is equal to 11 of the metre. The troy pound of the mint is the United States standard weight

for coinage. It is of brass of unknown density, and therefore not

suitable for a standard of mass. It was derived from the British standard troy pound of 1758 by direct comparison. The British avoirdupois pound was also derived from the latter and contains

7,000 grains troy. The grain troy is therefore the same as the grain

avoirdupois, and the pound avoirdupois in use in the United States

is equal to the British pound.

2-20462234 pounds avoirdupois = 1 kilogramme.

In Great Britain the legal metric equivalent of the imperial gallon

is 4-54346 litres, and of the imperial bushel 36-3477 litres. The length of a nautical mile, as given below, is that adopted by

the United States Coast Survey many years ago, and defined as the

length of a minute of arc of a great circle of a sphere whose surface

is equal to the surface of the earth (the Clarke spheroid of 1866).

1 foot = 0-304801 metre, 9-4840158 log.

1 fathom - 1-829 metres.

1 Gunter's chain = 20-1168 metres.

1 square statute mile - 259-000 hectares.

1 nautical mile = 1853-25 metres.

1 avoirdupois pound = 453-5924277 grammes.

15432-35639 grains = 1 kilogramme. *****

By the concurrent action of the principal Governments of the world, an International Bureau of Weights and Measures has been

established near Paris. Under the direction of the International Committee, two ingots were cast of pure platinum-iridium in the proportion of 9 parts of the former to 1 of the latter metal. From

one of these a certain number of kilogrammes were prepared; from

the other a definite number of metre bars. These standards of

weight and length were intercompared without preference, and

certain ones were selected as international prototype standards. The

others were distributed by lot, in September, 1889. to the different Governments, and are called national prototype standards. Those

apportioned to the United States were received in 1890 and arc in the keeping of this office. The metric system was legalized in the United States in 1866. The International Standard Metre is derived from the Metre des Archives, and its length is defined by the distance between two lines at 0° centigrade on a platinum-iridium bar deposited at the Inter- national Bureau of Weights and Measures. The International Standard Kilogramme is a mass of platinumiridium deposited at the same place, and its weight in vacuo is the same as that of the Kilogramme des Archives. The litre is equal to a cubic decimetre, and it is measured by the quantity of distilled water which, at its maximum density, will counterpoise the standard kilogramme in a vacuum, the volume of such a quantity of water being, as nearly as has been ascertained, equal to a cubic decimetre.

Appendix 4. The International Nautical

Mile

The following announcement is quoted from the

National Bureau of Standards Technical News Bulletin of August 1954. Adoption of Internalidnal Nautical Mile

Beginning on July 1, 1954, the National Bureau of Standards will

use the International Nautical Mile in lieu of the U.S. Nautical Mile. This decision, replacing the U.S. Nautical Mile of 1,853.248 meters

(6,080.20 feet) by the International Nautical Mile of 1,852 meters

(6,076.10333 - . . feet), confirms an official agreement between the

Secretary of Commerce and the Secretary of Defense to use the In- ternational Nautical Mile within their respective departments. The use of a mile derived from the length of a degree of the earth's meridian is very old. It is believed that the Chaldean astronomers

determined the length of such a unit. Miles of this sort have been

variously called meridian miles, geographical miles, sea miles, and

nautical miles, and they have differed greatly in magnitude, some

of the values providing 10, 12, 15, and 60 miles to a degree. The

British and the U.S. nautical miles were each derived by taking 60

nautical miles per degree, but the values adopted were not the same. The nautical mile adopted by the British Admiralty equals 6,080

British feet, while the U.S. nautical mile has had the adopted value

of 1,853.248 meters, from which the equivalent 6,080.20 U.S. feet has been derived. The British foot is shorter than the U.S. foot by 1 part in 400,000, an amount which is of no importance in the ordinary transactions of everyday life but which is very important

in precise measurements.

In 1929 the International Hydrographic Bureau obtained an agree- ment from a large number of countries to adopt a value of 1,852 meters for the nautical mile, the unit thus defined to be called the

International Nautical Mile. However, at the same time Great

Britain, the U.S.S.R., and the United States did not accept this value, each country preferring to retain the nautical mile to which

it had been accustomed.

Finally, in 1953 an informal group from the Department of Defense and the Department of Commerce considered a proposal for inter- national standardization of abbreviations for the knot and the mile. At this meeting the general situation regarding the nautical mile

29
was discussed, and the belief was expressed that a change from

1,833.248 meters to 1,852 meters would not affect nautical charts, the calibration of navigational instruments, or navigation. Because

there seemed to be no sound reason why the International Nautical Mile should not be adopted in this country, the Departments ot Gjmmcrce and Defense agreed to accept this value as of July 1, 1954, the announcement to be made by the National Bureau of Standards.

Identical directives, in the names of the two departments, have

been mutually adopted. The Department of Commerce directive

is as follows:

Adoption of International Nautical Mile

I. Purpose To adopt the International Nautical Mile for use as a standard

value within the Department of Commerce.

II. Implementation

After the effective date of this directive, the International Nautical Mile (1,852 meters, 6,076.10333 . . . feet"), shall be used within

the Department of Commtrce as the standard length of the nautical

mile.

III. Effective date This directive is effective 1 July 1954.

It will be noted that in the forgoing announcement

one of the equivalents of the international nautical

mile is stated as 6,076.10333 . . . feet. The three

dots following the last digit indicate a continuing

repetition of the digit 3- By reference to appendix 5, it will be found that

the equivalent of the international nautical mile in

feet is stated as approximately 6,076.11549 international feet; this latest value represents no change in the length of the nautical mile—1852 meters—but

is merely a restatement of the equivalent in terms of

the international foot which is shorter than the for- mer United States foot by two parts in a million.

Appendix 5. The United States Yard

and Pound

The following statement of the Department of

Commerce concerning a refinement of values for the yard and the avoirdupois pound, approved June 25,

1959, is quoted from the Federal Register of July 1, 1959:

Refinement of Values for the Yard and the Pound

Background. The National Bureau of Standards, founded in 1901,

is authorized by statute (U.S. Code, Title 15, Ch. 7, sec. 272) to undertake "The custody, maintenance, and development of the national standards of measurement and the provision of means and methods for making measurements consistent with these standards.

* * *" Under this authority the National Bureau of Standards

has sought to refine and extend the standards to meet the continuing

requirements of science and industry for increased accuracy and uni- formity of measurement.

Since 1893 the National Bureau of Standards and its predecessor agency, the Office of Standard Weights and Measures of the Treasury Department, have derived the yard and the pound and the multiples

and submultiples of these units from metric standards, namely the

international meter and the international kilogram. The original announcement of this derivation, together with the numerical ratios upon which the derivations were based, is given in Bulletin 26, "Fundamental Standards of Length and Mass", of the U.S. Coast and Geodetic Survey, approved for publication April 5, 1893, by the

Secretary of the Treasury. An amendment to the 1893 Bulletin was made in 1894 in which there was a small adjustment in the jxjund- kilogram ratio to bring it into closer agreement with the British Imperial pound.

In the latter half of the period since 1893 minor but troublesome

discrepancies have developed among various groups, both in this country and abroad, that are concerned with very accurate measure- ments involving yard and pound units or their customary multiples and submultiples. As a result of study and negotiation, it has de- veloped that most of the discrepancies can be resolved and a high

degree of measurement uniformity obtained by small refinements of

the ratios defined in the 1893-94 bulletins relating the yard and pound

to the meter and kilogram. Accordingly, the following announce- ment is made:

Announcement. Effective July 1, 1959, all calibrations in the U.S. customary system of weights and measures carried out by the National Bureau of Standards will continue to be based upon metric measurement standards and except those for the U.S. Coast and

Geodetic Survey as noted below, will be made in terms of the following exact equivalents and appropriate multiples and submultiples:

1 yard =0.914 4 meter

1 pound (avoirdupois) =0.453 592 37 kilogram

Currently, the units defined by these same equivalents, which have

been designated as the International Yard and the International Pound, respectively, will be used by the National Standards Laboratories of Australia, Canada, New Zealand, South Africa, and United Kingdom; thus there will be brought about international accord on

the yard and pound by the English-speaking nations of the world, in precise measurements involving these basic units. Any data expressed in feet derived from and published as a result of geodetic surveys within the United States will continue to bear

the following relationship as defined in 1893:

, ^ 1200

3937 """^

The foot unit defined by this equation shall be referred to as the U.S'

j Survey Foot and it shall continue to be used, for the purpose given

| herein, until such a time as it becomes desirable and expedient to i readjust the basic geodetic survey networks in the United States, after which the ratio of a yard, equal to 0.914 4 meter shall apply. Relation to Peeviously Defined Standards I

I In 1866 (U.S. Code 1952 Ed., Titles 15, Ch. 6, sees. 204 and 205)

the Congress legalized the use of the metric system within the United

States. The law also established approximate equivalents be, 'reu customary and metric measures. The above ratios between the yrid i and pound and metric measures as well as those defined in the 1893-94

bulletins are consistent with the ratios established by Congress in 1866 within the limits of accuracy by which the latter arc expressed.

Yard. In the 1893 Bulletin the yard was defined as:

, J 3600

3937

which results in the approximate relation

1 yard= 0.914 401 83 meter 30
Thus the new value for the yard is smaller by 2 parts in one million than the 1893 yard. Numerical measures expressed in terms of the new unit will, therefore, be increased by 2 parts in one million. Pound. The pound was defined in the 1893 Bulletin as:

1

1 pound (avoirdupois)

1.10462 kilogram

The 1894 amendment based on a recent determination of the British Imperial pound, gave the ratio as:

1 pound (avoirdupois)=

1 2.20462234 kilogram

which results in the approximate relation

:

1 pound (avoirdupois)=0.453 592 4277 kilogram

Thus the new value for the pound is smaller by about 1 part in 10

million than the 1894 pound. Numerical measures expressed in terms of the new unit will, therefore, be increased by about 1 part in 10 million. Changes concern science and precision tools. Such small changes are beyond the limits of accuracy by which many reference standards

are now calibrated by the National Bureau of Standards, including

the standards furnished to or calibrated for the State governments.

Therefore, the refinements in the definitions of the yard and the pound will have no effect at all upon ordinary trade and commerce. The differences are significant, however, in a number of very precise metrological determinations such as are found in the precision machine tool and instrument industries and in certain scientific activities. Standard inch. The value for the inch, derived from the value for

the yard effective July 1, 1959, is exactly equivalent to 25.4 milli- meters. It may be noted that this value was approved by the American Standards Association for "Inch-millimeter Conversion

for Industrial Use" in 1933 (ASA Standard B48. 1-1933), was adopted

by the National Advisory Committee for Aeronautics in 1952, and

has been adopted by many standardizing organizations in other

countries.

Relation to grain. The new conversion factor for the pound is exactly divisable by 7 and results in the following exact value for the grain: " 1 grain =0.064 798 91 gram

The grain is the common unit of the avoirdupois, apothecary, and

troy systems, there being 7000 grains in the avoirdupois pound and

5760 grains in the apothecary pound and in the troy pound.

Nautical mile. On July 1, 1954, it was announced that the Secre- tary of Commerce and the Secretary of Defense had agreed officially that the International Nautical Mile would henceforth be used within their respective departments. The International Nautical Mile is based on the meter and is equal to 1852 meters. Based on

the yard-meter relationship then in use, the International Nautical Mile was shown as being equivalent to 6,076.10333 feet. Under the new conversion factor, the International Nautical Mile is equivalent to 6,076.11549 International feet approximately. (For a detailed treatment of the Federal basis for weights and

measures, see National Bureau of Standards Circular 593, The Federal

Basis for Weights and Measures, for sale by the Superintendent of Documents, U S. Government Printing Office, Washington 25, D.C.,

price 30 cents.)

[seal] a. v. Astin,

Director, National Bureau of Standards. H. Arnold Karo,

Kear Admiral,

Director, Coast and Geodetic Survey. Approved: June 25, 1959.

F. H. Mueller,

Under Secretary of Commerce.

[F.R. Doc. 59-5442; Filed, June 30, 1959; 8:45 a.m.]

Appendix 6. Adoption of the Wavelensth Definition of the Meter

The following account concerning the adoption of the wavelength definition of the meter is quoted from

the National Bureau of Standards Technical News

Bulletin of December 1960:

Wavelength o\ Kr^^ Light Becomes New International Standard of Length

On October 14, I960 the world adopted a new international standard of length—a wavelength of light—replacing the metei bar which

had served as the standard for over 70 years. The action was taken by the 11th General Conference on Weights and Measures, which

met in Paris. Dr. Allen V. Astin, NBS Director, headed the American delegation

to the Conference. The delegation also included Louis Polk, Presi- dent, Sheffield Corporation; Elmer Hutchisson, Director, American

Institute of Physics; A. G. McNish, Chief, Metrology Division, NBS; T. H. Osgood, U.S. Scientific Attache, London, and Marten Van Heuven and Benjamin Bock, U.S. State Department.

Other actions taken by the Conference included the establishment

of a central facility at the International Bureau of Weights and Measures for international coordination of radiation measurements, confirmation of a new definition of the second of time, and adoption of

refinements in the scales for temperature measurements. The new definition of the meter as 1,650,763.73 wavelengths of

the orange-red line of krypton 86 will replace the platinum-iridium meter bar which has been kept at Paris as an international standard

for length since 1889 under the Treaty of the Meter. These actions of the General Conference are of great importance

to those engaged in precision measurements in science and industry. For many years the world has relied on a material standard of

length—the distance between two engraved lines on the International Meter Bar kept at Paris Duplicates of the International Standard were maintained in the standards laboratories of other countries of the world. From time to time it was necessary to return these duplicates to Paris for recalibration, and occasionally discrepant

results were obtained in these recalibrations. Also, there was doubt

in the minds of some scientists regarding the stability of the Inter- national Meter Bar. The new definition of the meter relates it to a constant of nature, the wavelength of a specified kind of light, which

31
is believed to be immutable and can be reproduced with great accu- racy in any well<quipped laboratory. Thus it is no longer necessary

to return the national standards of length to Paris at periodic inter- vals in order to keep length measurements on a uniform basis throughout the world. Also it is possible to measure some dimensions more accurately in terms of the new definition than was possible

before. The meter bars which have served as standards of length

throughout the world for over 70 years will not be discarded or

placed in museums because of this decision, the Conference said. They will remain important because of the ease with which they can be used for certain types of measurement and for comparison measurements between national laboratories. This new definition of the meter will not materially change the measurement of length nor in any way the relation between the English and Metric units. Careful experiments performed at the National Bureau of Standards by the team of A. G. Strang, K. F. Nefflen, J. B. Saunders, B. L. Page, and D. B. Spangenberg immediately prior to the meeting of the Conference confirmed that the wavelength standard and the metal standard are in satisfactory agreement. The inch now becomes equal to 41,929.399 wavelengths

of the krypton light Similar measurements performed by the National Research Council

in Canada, by Dr. K. M. Baird and his associates, are in substantial

agreement with the National Bureau of Standards results. By

adoption of the new definition, the standard of length which has

been used by spectroscopists for the past 50 years is brought into agreement with that used in other branches of science, thus increas- ing the unification of systems of measurement throughout the

scientific world. The orange-red wavelength is precisely described as the wavelength in vacuum of the radiation corresponding to the transition between the levels Ipio and Sd^ of

the atom of krypton 86.

The author acknowledges with gratitude the assis- tance he has received in the earlier stages of the

preparation of this publication from Ralph W. Smith,

himself an ardent worker for uniform weights and

measures in the United States, and in all stages from

Malcolm W. Jensen.

32
Appendix 7

National Bureau of Standards METRIC SYSTEM OF WEIGHTS AND

MEASURES

Guidelines for Use

Section 403 of Pub. L. 93-380 states the

policy of the United States to encourage

educational agencies and institutions to prepare students to use the metric sys- tem of measurement as part of the regular education program and authorizes the U.S. Commissioner of Education to carry out a program of grants and contracts to fulfill this policy. Subsection 403

(a)(3) states, "For the purposes of this section, the term 'metric system of measurement' means the International Sys- tem of Units as established by the General Conference of Weights and Measures

in 1960 and Interpreted or modified for the United States by the Secretary of Comnlerce." The National Bureau of Standards is resfxjnsible for "the custody,

maintenance, and development of the national standards of measurement" (15 U.S.C. 272) , and the Secretary has desig- nated NBS to Implement his responsibilities under subsection 403(a)(3). Pursuant to his authority under section 403, the U.S. Commissioner of Education has

requested that NBS publish guidelines for use of the International System of Units,

as Interpreted and modified for the United States. Accordingly, and in implementation of the Secretary's responsibilities under subsection 403(a) (3) , the

following tables and associated materials

set forth guidelines for use of the Inter- national System of Units (hereinafter

"SI"), as Interpreted and modified for the United States by NBS on behalf of the Secretary of Commerce. The SI Is constructed from seven base

units for independent quantities plus two

supplementary units for plane angle and

solid angle, listed in Table 1.

Table 2—SI derived unite with tpeeial namet

Quantity Symbol

SI BASE UNITS

length metre (meter) i m

mass'..- kilogram kg

time second s electric current ampere A

thermodynamic kelvin. K

temperature.

amount of substance. . mole mol

luminous intensity . . . candela cd

SI SUPPLEMENTARY UNITS

plane angle.... radian

solid angle steradian.

1 Both spellings are acceptable.

' "Weight" is the commonly used term for "mass."

3 It is acceptable to use the Celsius temperature (symbol 0 defined by ( = r-To where T Is the thermodynamic temperature, expressed in kelvins, and ro=273.15 K by definition. The unit "degree Celsius" is thus equal

to the unit "kelvin" when used as an interval or differ- ence of temperature. Celsius temperature is expressed

in degrees Celsius (symbol "C). Units for all other quantities are derived from these nine units. In Table 2 are listed 17 SI derived units with special names which were derived from the base and supplementary units in a coherent manner, which means in brief, that they

are expressed as products and ratios of the nine base and supplementary units without numerical factors.

Quantity Name

Expression Symbol in terms of other units

frequency hertz.

force newton.. HzN

. pascal Pa

Joule _. J watt coulomb.

.

volt..

pressure, stress., energy, work,

quantity of heat, power radiant flux, quantity of elec- tricity, electric charge,

electric potential, potential differ- ence, electromotive force. capacitance farad F

electric resistance.. . ohm £2 conductance Siemens S magnetic flux weber Wb

magnetic flux tesla T

density. inductance henry H

luminous flux lumen Im

Illuminance lux Ix activity (radio- becquerel Bq

active). absorbed dose gray. Gy

m-kg/s' N/m» N-m

J/s A-s

W/A

C/V V/A

A/V

V-s Wb/m> Wb/A

cd'Sr Im/m'

s-i

J/kg

All other SI derived units, such as those

in tables 3 and 4, are similarly derived in a coherent manner from the 26 base, sup- plementary, and special-name SI units. Table 3.—Example> of SI derived unite, eipristed in terme of bate unite

For use with the SI units there is a set of 16 prefixes (see table 5) to form multiples and submultiples of these units. Table b.—SI prefixee

Factor Prefix Symbol

10" exa E

ion peta P

10n.._ tera T

10» glga O

10» mega - M W kilo k

10' hecto h

10' - -- deka da

10-' decl d

10-' centi - c

10-' mlUi - m

10-* micro fi 10r> nano n

10-" pico p

lO-'i femto f 10-n.. atto a

Certain imlts which are not part of the SI are used so widely that It is Impractical to abandon them. The units that are accepted for continued use in the United States with the International System are listed in table 6. Table i.— Unite in use with the internatimal eyetem

Name Symbol Value in SI unit

Quantity SI unit Unit symbol

area. square metre. ._ volume cubic metre

speed, velocity metre per second

acceleration metre per second

squared. wave number 1 per metre

density, mass kilogram per cubic

density. metre.

current density ampere per square

metre. magnetic field ampere per metre.. .

.

strength. concentration (of mole per cubic metre, amount of substance).

specific volume cubic metre per kilo- gram. luminance candela per square

metre.

m'

m'

m/s

m/s' m-i

kg/m' A/m' A/m

mol/m'

m'/kg

cd/m'

minute min

hour h

day d

degree " minute '

second "

litre (liter) ' 1 metric ton or tonne... t

1 inin=60 s

1 h = 60 min=3 600 s

1 d = 24 h=86 400s r = (T/180) rad

l' = (l/60)° = (ir/10 800) rad

1" = (1/60)' = (W648 000) rad

1 1=1 dm' = 10-im'

1 1=103 kg

I Both spellings are acceptable. In those cases where their usage is already well established, the use, for a

limited time, of the following units is accepted, subject to future review.

nautical mile knot angstrom

standard atmosphere

hectare barn

bar

are

gal

'

curie rontgen

rad

Table 4.Examples of 81 derived units expressed by means of special names

Quantity

1 Not gallon. Metric units and their symbols other than those enumerated above are not

part of the International System of

Units. Accordingly, the following units and terms listed In the table of metric

units in section 2 of the act of July 28. 1866. that legalized the metric system of weights and measures In the United

States, are no longer accepted for use in the United States: myrlameter

stere minier or tonneau

quintal myrlagram

kilo (for kilogram) For more information regarding the

International System of Units, contact

the. Metric Information OfiBce, National Bureau of Standards, U.S. Department

of Commerce, Washington, D.C. 20234. Dated: June 1, 1975. Richard W. Roberts,

Director. [FR Doc.75-15798 PUed 6-18-76;8:45 am]

Note: The kilogram is the only SI unit with a prefix.

Because double prefixes are not to be used, the

prefixes of Table 5, in the case of mass, are to be

used with gram and not with kilogram.

dynamic viscosity., moment offeree...

surface tension heat flux density,

Irradiance. heat capacity, entropy.

specific heat

capacity, specific entropy.

specific energy thermal conductivity. energy density

electric field strength,

electric charge

density,

electric flux density. permittivity permeability molar energy molar entropy, molar heat

capacity.

Name Unit symbol

pascal second Pa-s metre newton.. - N-m

newton per metre N/m

watt per square W/m'

metre.

joule per kelvin J/K

joule per kilogram J, (kg-K)

kelvin.

joule per kilogram J/kg watt per metre W/(m-K)

kelvin.

joule per cubic J/m'

metre.

volt per metre V/m

coulomb per cubic C/m'

metre. coulomb per square C/m'

metre.

farad per metre F/m

henry per metre. H/m

joule per mole J/mol

joule per mole kelvin.. J/(mol-K)

33
Appendix 8

DEPARTMENT OF COMMERCE

National Bureau of Standards

CUSTOMARY SYSTEM OF WEIGHTS AND MEASURES

Commercial Weights and Measures Units

By virtue of the authority vested in the Secretary of Commerce

by 15 U.S.C. 272 and delegated to the National Bureau of Standards by Department Order 90-A, the Bureau is charged with the responsibility for The custody, maintenance, and development of the

national standards of measurement, * * ihe method employed

for disseminating information on weights and measures units has been through official National Bureau of Standards publications. However, all such units have never been listed together in any

Federal legislation or in the Federal Register. On February

27, 1968, in the House Committee on Science and Astronautics Report No. 1107, accompanying H.R. 13058, legislation to repeal the Standard Container Act of August 31, 1916 (39 Stat. 673; 15 U.S.C. 251-256), and the Standard Container Act of May 21, 1928 (45 Stat. 685; 15 U.S.C. 257-257i), and amend the Fair Packaging and Labeling Act of November 3, 1966 (80 Stat. 1296; 15 U.S.C.

1451), the following Committee view was expressed: Testimony revealed that although standard weights and measures

are defined in publications by the Bureau of Standards, these defini- tions are not defined by law nor have they been published in the Federal Register. Consequently, the Committee recommends that the Secretary of Commerce cause to be published in the Federal

Register a listing of the common weights and measures used in normal commerce throughout the United States and relate them to the standards developed in accordance with existing law, 15 U.S.C.

272.Commercial units of weight and measure in common use are based on the yard and the avoirdupois pound. The yard and avoirdupois

pound were last defined in the Federal Register of July 1, 1959,

in terms of the national standards of length and mass: The meter and

the National Prototype Kilogram. From the two units, the yard and

the pound, are derived all other U.S. Customary multiple and

submultiple units that will be found in ordinary commerce. They

are defimed as

:

1 yard =0.914 4 meter '

1 pound (avoirdupois)=0.453 592 37 kilogram * LINEAR MEASURE

U.S. CUSTOMARY

12 inches = l foot =0.304 8 meter '

3 feet = l yard=0.914 4 meter * 5,280 feet = l statute mile =1.609 kilometers

6,076.115 feet = l International Nautical Mile = 1.852 kilometers '

METRIC

10 millimeters =1 centimeter 10 centimeters = 1 decimeter

10 decimeters =1 meter

10 meters =1 dekameter

10 dekameters = l hectometer

10 hectometers =1 kilometer

AREA MEASURE

U.S. CUSTOMARY

144 square inches = 1 square foot =0.092 9 square meter

9 square feet =l square yard=0.836 1 square meter

43,560 square feet =l acre=0.404 7 hectare 640 acres =1 square mile =259 hectares

1 square mile =l section =259 hectares 36 sections =1 township =932 4 hectares

METRIC

100 square millimeters = 1 square centimeter 10,000 square centimeters = 1 square meter

100 square meters =1 are 100 ares =l hectare 100 hectares = 1 square kilometer

WEIGHT

U.S. CUSTOMARY (AVOIRDUPOIS)

437.5 grains = l ounce=28.349 5 grams

7,000 grains = i pound =0.453 592 37 kilogram

16 ounces = l pound=0.453 592 37 kilogram

2,000 pounds =l short ton=0.907 2 metric ton

2,240 pounds =1 long ton = 1.016 metric tons

METRIC

1 Denotes exact figures.

10 milligrams = 1 centigram

10 centigrams = 1 decigram

10 decigrams = l gram

10 grams = 1 dekagram

10 dekagrams = 1 hectogram

10 hectograms = 1 kilogram

1,000 kilograms = 1 metric ton

FEDERAL REGISTER, VOL. 33, NO. 146—SATURDAY, JULY 27, 1968

34
Appendix 8 —Continued

I CAPACITY, OR VOLUME, LIQUID MEASURE

U.S. CUSTOMARY

1 gallon=231 cubic inches =3.785 4 liters 4 fluid ounces = 1 gill =0.118 3 liter

4 gills =l pint=0.473 2 liter 2 pints =l quart=0.946 4 liter 4 quarts = 1 gallon =3.785 4 liters

j METRIC

' 10 milliliters = 1 centiliter 10 centiliters = 1 deciliter

I 10 deciliters = 1 liter 10 liters =1 dekaliter

10 dekaliters = 1 hectoliter 10 hectoliters = 1 kiloliter CAPACITY, OR VOLUME, DRY MEASURE

U.S. CUSTOMARY

1 bushel =2,150.42 cubic inches = 35.239 1 liters

I 2 dry pints = l dry quart = 1.101 2 liters 8 dry quarts = 1 peck =8.809 8 liters 4 pecks =l bushel=35.239 1 liters The accepted volume of a barrel in the United States varies

significantly depending both on the commodity for which it is used and on how it is defined in State law (varying from State-to-State).

I METRIC

I The volumetric units are the same for both liquid and dry measure

in the Metric System.

Cubic Measure

U.S. Customary

1,728 cubic inches =l cubic foot=0.028 316 8 cubic meter

27 cubic feet =l cubic yard =0.764 554 9 cubic meter

Metric

1,000 cubic millimeters = 1 cubic centimeter

1,000 cubic centimeters = 1 cubic decimeter

1,000 cubic decimeters = 1 cubic meter

Special Units The unit used for the sale of firewood is the cord of 128 cubic feet. The unit used for the sale of precious stones is the Metric Carat

of 200 milligrams.

The units used for over-the-counter sales of precious metals in the United States are troy units. Troy Weight

24 grains =l pennyweight = 1.555 17 grams

20 pennyweights = 1 ounce troy =31. 103 47 grams

12 ounces troy = l pound troy =0.373 242 kilogram

The apothecaries system of units, once widely used in the United

States for pharmaceutical purposes, is now used only very little. Usage of the Metric System has replaced the apothecaries system at the manufacturing level, and at most of the retail level.

Electricity and Natural Gas When a consumer is billed for having used electricty, what has

been sold is electrical energy, and that energy is expressed in terms

of kilowatt-hours. One kilowatt-hour equals 3,600,000 joules (the

joule is the unit of energy in the International System of Units). Consumption of natural gas normally is expressed in terms of

therms. One therm equals 105,480,400 joules.

Dated: July 15, 1968. A. V. Astin, Director.

[F.R. Doc. 68-8953; Filed, July 26, 1968; 8:45 a.m.]

FEDERAL REGISTER, VOL. 33, NO. 146—SATURDAY, JULY 27, 1968

35
Appendix 9

DEPARTMENT OF COMMERCE

National Bureau of Standards

CUSTOMARY SYSTEM OF WEIGHTS AND MEASURES

Commercial Weights and Measures Units

In the Federal Register of July 27, 1968 (33 FR 10755), the National Bureau of Standards, in accordance with a recommendation

of the House Committee on Science and Astronautics and pursuant

to the responsibility of the National Bureau of Standards for ' the

custody, maintenance, and development of the national standards of measurement" (15 U.S.C. 272), published a listing of the common

weights and measures used in normal commerce throughout the United States, and related them to the standards developed in accordance with existing law. In connection with the notice of July 27, 1968, the following explanatory material will assist in the proper interpretation and application of the data in column three under "Linear Measurement, U.S. Customary," and under "Area

Measurement, U.S. Customary": As the July 27, 1968 notice states, all U.S. Customary Units of

linear and area measurement that will be found in ordinary commerce are derived from the yard. The yard was last defined in a notice in the Federal Register of July 1, 1959 (24 FR 5348), as being

exactly equal to 0.9144 meter. The foot defined by the equations

:

3 feet =l yard =0.9144 meter, exactly

1 foot=0.3048 meter, exactly

is known as the International Foot. In addition, the July 1, 1959

notice defines the U.S. Survey Foot as follows:

1200

1 survey foot = meter, exactly

^ 3937

or

1 survey foot=0.304 800 61 meter, approximately

Accordingly, it is necessary to differentiate between the international foot, used for engineering, and the U.S. survey foot, used for mapping and land measurement. The metric equivalents listed in the July 27, 1968 notice for land measurements: statute mile (U.S. survey mile), acre, square mile, section, and township are approxi- mate; metric equivalents to more figures can be determined from the

survey foot. For example, the U.S. survey mile equals 1.609 347

kilometers, approximately, whereas the international mile equals 1.609 344 kilometers, exactly. Metric equivalents of all surveyor's

units, e.g., links, rods, and chains, are derived from the survey foot. The relationship

1 international nautical mile =1.852 kilometers

is exact, but the relationship

6 076.115 international feet =l international nautical mile

is not exact.

Dated: January 17, 1975. Richard W. Roberts,

Director.

I

Note.—This document is republished from the issue ofJanuary 22, 1975 (40 FR 3486). [FR Doc. 75-2011 Filed 1-21-75; 8:45 am]

FEDERAL REGISTER, VOL. 40, NO. 23—MONDAY, FEBRUARY 3, 1975

36 is U.S. GOVERNMENT PRINTING OFFICE : 1976 O—216-296