AN IMPROVED MATHEMATICAL OR PLOTTING INSTRUMENT, WHICH HE INTENDS TO DENOMINATE A PROTRACTING TRIGONOMETER
Year: 1860

page_text: LETTERS PATENT to William Edward Newton, of the Office for Patents,
66, Chancery Lane, in the County of Middlesex, Civil Engineer, for the
Invention of "AN IMPROVED MATHEMATICAL OR PLOTTING INSTRUMENT,
WHICH HE INTENDS TO DENOMINATE A PROTRACTING TRIGONOMETER."-A
communication from abroad by Josiah Lyman, of Lenox, in the
County of Berkshire and State of Massachusetts, United States of
America.
PROVISIONAL SPECIFICATION left by the said William Edward Newton
at the Office of the Commissioners. of Patents, with his Petition,
on the 24th July 1860.
I, WILLIAM EDWARD NEWTON, of the Office for Patents, 66, Chancery Lane.
in the County of Middlesex, Civil Engineer, do hereby declare the nature of
the said Invention for "AN IMPROVED MATHEMATICAL OF PLOTTING INSTRUMENT
WHICH I INTEND TO DENOMINATE A PROTRACTING TRIGONOMETER," to be as
follows:-
This Invention of an improved mathematical or plotting instrument consists
of a combination of a protractor with a vernier scale, a draughting rule.or
straight edge, provided with scales of different kinds according to the uses for
which the instrument is intended to be employed; and lastly, there is a sliding

page_text: vernier scale which will admit of observations being read off with very great
accuracy. The instrument is intended to be used for plotting surveys and for
all purposes of draughting, wherein courses and distances, or lines and angles,
are required to be laid down, or where lines and angles already laid down are
required to be measured. The principal uses and properties of the instrument
will therefore be indicated when it is denominated as a protracting trigonometer.
A semicircular protractor divided in the ordinary manner is adapted to the
pivot of a cross bar, which forms the head of a straight edge or draughting
rule, to which is adapted a scale plate having a variety of scales marked
thereon. This straight edge and scale may be made of any convenient length,
and the scale plate is provided with a vernier marked with corresponding
scales, and is moveable along the scale plate. The left-hand end of the
draughting rule or straight edge projects beyond the cross piece or head, and
a vernier for the protractor is adapted thereto, so that lines at any angle to a
base or perpendicular may be laid down with facility, and when laid down the
distance between any two points on the land may be measured by means of
the scale plate and its vernier.
SPECIFICATION in pursuance of the conditions of the Letters Patent, filed
by the said William Edward Newton in the Great Seal Patent Office
on the 24th January 1861.
TO ALL TO WHOM THESE PRESENTS SHALL COME, I, WILLIAM
EDWARD NEWTON, of the Office for Patents, 66, Chancery Lane, in the County
of Middlesex, Civil Engineer, send greeting.
WHEREAS Her most Excellent Majesty Queen Victoria, by Her Letters
Patent, bearing date the Twenty-fourth day of July, in the year of our Lord
One thousand eight hundred and sixty, in the twenty-fourth year of Her reign,
did, for Herself, Her heirs and successors, give and grant unto me, the
said William Edward Newton, Her special license that I, the said William
Edward Newton, my executors, administrators, and assigns, or such others as
I, the said William Edward Newton, my executors, administrators, and assigns,
should at any time agree with, and no others, from time to time and at
all times thereafter during the term therein expressed, should and lawfully
might make, use, exercise, and vend, within the United Kingdom of Great
Britain and Ireland, the Channel Islands, and Isle of Man, an Invention
for "AN IMPROVED MATHEMATICAL OB PLOTTING INSTRUMENT, WHICH I INTEND TO S
DENOMINATE A PROTRACTING TRIGONOMETER'," being a communication from

page_text: abroad, upon the condition (amongst others) that I, the said William Edward
Newton, by an instrument in writing under my hand and seal, should par-
ticularly describe and ascertain the nature of the said Invention, and in
what manner the saine was to be performed, and cause the same to be filed
in the Great Seal Patent Office within six calendar months next and imme-
diately after the date of the said Letters Patent.
NOW KNOW YE, that I, the said William Edward Newton, do hereby
declare the nature of the said Invention, and in what manner the same is
to be performed, to be particularly described and ascertained in and by the
following statement, reference being had to the Drawings hereunto annexed,
and to the letters and figures marked thereon (that is to say):-
This Invention of "an improved mathematical or plotting instrument, which
I intend to denominate a protracting trigonometer,' is intended to be used for
plotting surveys and for all purposes of draughting wherein courses and
distances, or lines and angles, are required to be laid down upon paper, or
where lines and angles already laid down are required to be measured.
In the accompanying Drawings Fig. 1 is a plan view of the instrument, the
several parts thereof being shewn of the real size and exact proportions, except
that a portion of the blade of the instrument is shewn as being broken off;
Fig. 2 is a plan view of the under side of the instrument, the scale plate being
removed; Fig. 3 is a longitudinal vertical section of the instrument through
its centre, the scale plate being removed; Figures 4 represent three transverse
sections of the guides and scale plate with which they are connected, the sections
being taken through their respective knobs or thumb pieces and the verniers ;
Fig. 5 is a plan view, and Fig. 5 a side view of the protractor vernier; Fig. 6
is a plan view, and Fig. 6° a side view of the attached end of the rule taken
out of the frame; Fig. 7 is a plan view, and Fig. 7 a side view of the
protractor frame, the protractor, the rule, and the parts connected with them
being removed.
It will be seen that the improved instrument principally consists of a com-
bination of the protractor, draughting rule, and sliding vernier scale.
P is a semicircular protractor graduated to seventy degrees on each side of
its north point or meridian, and is seen with the graduated side up in Fig. 1,
and inverted in Fig. 2. It is made of brass or German silver, and should not
be more than one-tenth of an inch nor less than one-sixteenth of an inch
thick. It is provided with a socket piece of bronze attached to its centre for
receiving the pivot (P i, Figures 2 and 3).
In Fig. 1, N denotes north; E, east; and W, west. The Figures on one
side of N indicate the degrees of the arc or angle, and the degrees on the

page_text: other side of N the complement of the same.
The protractor is firmly and
permanently fastened in the frame F, r. P, V, is the protractor vernier reading
to minutes or seconds or less. It is made of brass or German silver, and is
shewn detached at Fig. 5 and Fig. 5. Or, in Figures 5 and 6 denotes
orifices for screws. V, Pi Fig. 5, indicates the vernier pivot which is to be
inserted in the vernier pivot orifice (V, P i, 0, Fig.
of the attached end of
the rule. This pivot has in its centre an orifice (P i, O, Fig. 5,) for the
insertion of the main pivots of the instruments (P i, Fig. 3). The protractor
vernier piece has besides two small cylindrical pieces of brass or German
silver attached to it, and seen in Fig. 5, for receiving the adjusting screws
(A, S, Fig. 1) whereby the vernier may be adjusted.
'
The
protractor frame (Fig. 7) is composed of brass or German silver. It
has additional to what is shown in Fig. 7, a strip of the same metal as the other
parts of the frame, and of nearly-the same thickness as the protractor, extend-
ing across the open space shown in Fig. 7, and permanently fastened to the
other parts of the frame. Its width and length coincide with the base of the
protractor shown in Fig. 2.
It therefore exactly obscures that base in the
vertical view, Fig. 1, while in this Figure it is itself clearly seen.
R (Figures 1, 2, 3, and 6) is the rule or straight edge. It is a steel plate
usually twenty-two or thirty inches long from the centre of its axis or pivot,
but varying in length to suit its specific use. Its width is two inches, and
thickness from one-sixteenth of an inch to one-twelfth of an inch. It is
represented as broken in the Figures, and to it is fastened the protractor
vernier by means of screws.
SP, (Fig. 1), is the scale plate. It is usually sixteen and a quarter or
twenty-five and a quarter inches long, but varying in length to correspond with
the rule, one and a half inches wide and about one-twentieth of an inch thick,
composed of steel or German silver. It may be graduated with nine scales of
different units of division (as shown in Fig. 1) or less, and these units may
be subdivided into tenths, as in the Drawing, or into eighths or twelfths or any
other number of parts required, in order to correspond with the specific use
for which the instrument is intended to be employed.
A. G. and V, G, are the attached and vernier guides respectively. The
attached guide A, G, is permanently fastened to the scale plate, while the
vernier guide V. G. slides on the same with a smooth casy motion. This
latter guide consists of two side pieces of German silver connected together
by two cross pieces of the same metal or of brass with rivets at right angles
with the latter pieces. These side pieces are so milled as to form two flanges
on the sides for guiding the scale plate as it slides on the rule. The cross

page_text: pieces are so milled as to receive the same number of verniers as there are
scales marked on the scale plate, each reading to the tenth part of the sub-
division or hundredth part of the corresponding unit, when the decimal sub-
division is used. By an expert these verniers are easily read to thousandths of
the units. There are passing through the cross pieces twice as many adjusting
screws as there are verniers, that is, two antagonist screws to each vernier or
one at each end. By means of these screws each vernier can be adjusted to
its corresponding scale. The attached guide has side pieces like those of the
vernier guide, connected together by a cross piece of brass or German silver
about one twenty-fourth of an inch thick, and both guides have pieces of brass
or German silver about one hundredth of an inch thick on the under side
rivetted or soldered to the side pieces for keeping the scale plate in its proper
position. On each side of the vernier guide, near its left hand end, there is a
deeply graduated vertical line or knife-edge groove, the two constituting a set
called unit grooves, indicated on the Drawing at Fig. 1, by the numeral 1;
and on the sides of the attached guide there are nine sets or less of grooves,
cach of which when the two guides are placed in contact is exactly one unit
of the corresponding scale distant from the unit grooves on the vernier guide.
The precise position of these grooves is shown in Fig. 1 by short graduated
marks connected with the nine sets of numerical figures 8, 10, 12, 16, 20, 24,
32, 40, 48. Besides these there are on the sides of the vernier guide three
other sets of grooves (indicated by the numeral 3), two units of the coarser
divisions to the right of the unit grooves. Their object is to increase the
available length of the scale plate in extreme cases. The design of all the
grooves is to guide both the eye and a needle-pointed prick in using the
instrument. The precise construction of the guides is shown in three sections
(Fig. 4) referred to above. These guides are so constructed that the scale
plate with the guides can slide smoothly without undue friction on the rule,
and can be removed at pleasure, or be instantly transferred to the opposite
side whenever the instrument is inverted.
V, C, shown in Figures 2 and 3, is a piece of brass or German silver forming
the vernier clamp. It is pressed firmly against the under side of the pro-
tractor by means of the vernier clamp screw V, C, S, and this draws down
the vernier firmly against the upper side of the protractor, as fully shown
in Fig. 3.
T, G. (Fig. 1), is the tangent clamp; T, S, the tangent screw, reacting
against the tangent spring Tsp.
Pi (Figures 1, 2, and 3) is the compound pivot made of brass or German
Lancs the nut now thomat being of the last namnt outl T

page_text: pivot is tightly screwed to the protractor vernier. The other part of it (con-
stituting the pivot proper) is slightly conical in its form and it is double, being
the pivot for both the protractor and its vernier.
In the accompanying Drawings all the Figures show the several parts of
the instrument of the real size and exact proportions, except the length of the
rule and scale plate, which in the Drawings are represented as broken off
short. An exactly rectangular draughting table is supposed to accompany the
instrument, the length of which table is to its breadth as six to five; one end
or side being assumed as north.
In using the trigonometer, its face Fa is placed in contact with one of the
ends, sides, or edges of the table. If the instrument be rightly adjusted and set
at its meridian or north point (that is, with O on the vernier coinciding with
N on the protractor) and placed in contact with that end or side of the table
which is assumed as north, and with its graduated side up, all lines drawn by
either edge of the rule will be meridians, (that is to say, when applied to laying
down or measuring azimuth or horizontal angles,) and when the instrument
thus set is placed in contact with either the east or west sides of the table,
all lines drawn by either edge of its rule will be parallels of latitude. If
the instrument is held in the left hand with the graduated sides up, the rule
in the right hand and the vernier clamp loosened by gradually bringing the
rule towards the body on the right side, the zero point of the vernier continu-
ally approaches the letter E on the protractor, till all angles can be obtained
between north and north, sixty degrees cast, or their opposite angles; and by
carrying the rule in the contrary direction, the same point continually
approaches the letter W, till all angles can be obtained between north and
north, sixty degrees west, or their opposite angles.
When the instrument is used for laying down angles of elevation or depres-
sion, the line representing the horizon becomes the meridian.
In the description thus far the trigonometer is supposed to lic or to be held
with the graduated side of the protractor upwards, but by inverting the instru-
ment (that is, turning the graduated side of the protractor downwards), set as
it is supposed it to be at north or south sixty degrees east, or north or south
sixty degrees west, placing it in contact with either the cast or west sides of
the table, and gradually carrying back the rule to its former north point, all
angles are obtained between north or south thirty degrees cast, or north or
south thirty degrees west, and ninety degrees, ninety degrees in this case
being the east or west points.
Hence in either position of the trigonometer there is in it a susceptibility of
producing fifteen degrees beyond what is actually necessary on both sides of the

page_text: meridian point. For an azimuth motion of forty-five degrees instead of sixty
degrees named above would give every possible course or point of the compass;
therefore, for all points between forty-five degrees and sixty degrees on each
side of the meridian the instrument may be used either side up, as convenience
may require, thus facilitating its adaptation to every variety of problem. The
arrangement of the protractor also permits of a test for every course.
For taking distances the scale plate is held by the knob of its attached guide
K, (Figures 1 and 4,) with one hand, and with the other the vernier guide by
its knob K is carried to the required distance on the scale plate, the units and
tenths being read on such one of the several scales as suits the case at the left
edge of the latter guide, and the hundredths and thousandths on the corre-
sponding vernier. Now, the protractor vernier being set and clamped at the
required angle, and the instrument slid on the table till the rule is brought
close to the starting point or dot on the paper, the scale plate, with its vernier
guide set at the required distance, is then slid on the rule, till the groove of
either the attached or vernier guide (as the case may require) coincides with
the same dot, when a second dot is made with a needle in the groove of the
other guide at the other end of the given distance. The scale plate is next
carefully lifted from the rule, and the two dots are connected, if necessary, by
fine lines drawn with a draughting pen or a hard pencil sharpened with a flat
point. The protractor vernier is then set at the next required angle, and the
instrument brought to its proper position close to the second dot; the vernier
guide of the scale plate is set at the next required distance, and the same ope-
ration is repeated, and so on, till the work is finished. In measuring towards
the face of the trigonometer the measurement must be from the vernier guide
to the other, and vice versa.
For obtaining angles and distances already laid down, the rule of the instru-
ment is brought to coincide with the different points on the paper, and the
protractor vernier having been clamped, the grooves of the guides aro brought
to coincide with the same points. The angle is then read off on the protractor
and the distance on the scale plate.
Having now described this Invention of "An Improved Mathematical or
Plotting Instrument, which I intend to denominate a Protracting Trigono-
meter," and having explained the manner of carrying the same into effect,
what I claim as new and desire to have secured to me by Letters Patent, is,--
First, the arrangement of the several verniers, limbs, scale, and rule in one
instrument, as above described, and for the purposes set forth.
Second, I claim the peculiar arrangement of the sliding vernier scale plate,
by which it can be applied with equal readiness and facility to either side of

page_text: the rule, so as to read the given angle and its complement in connection with
the given distance, or be used separately, as the case may require.
Third, I claim the arrangement set forth for adjusting the several verniers
of the scale plate to their corresponding scales.
In witness whereof, I, the said William Edward Newton, havo hereunto
set my hand and seal, the Twenty-fourth day of January, in the year of
our Lord One thousand eight hundred and sixty-one.
Witness,
J. W. MOFFATT,
66, Chancery Lane.
W. E. NEWTON. (L.S.)