The star-independent. [volume] (Harrisburg, Pa.) 1904-1917, 1915-02-19
COAST and CEODETIC SURVEY
A Descriptive Handbook Has Been Is-
sued by the Department of
! Commerce

Washington, d. c., Feb. 19.-The
Department of Commerce has issued es-
pccially for distribution at the Pana-
ma, Pacific International Exposition a
pamphlet entitled "United States
Coast and Geodetic Survey, Description
of its Work, Methods and Organiza-
tion."
While this work is intended for the
general reader it also gives a concise
account of the more important scien-
tifc features of the work of the Survey
and of improvements that have been
made in recent years in instruments
to hydrography there is a description
of the wire drag, an apparatus so val
liable in discovering hidden dangers
that escape detection by the ordinary
methol of sounding.
In the section relating to tides is a
brief description of the improved tide
predicting machine which with one op-
orator predicts the tides for one year
in advance for any port, and does the
work of 100 men. To set the machine
for any station and tabulate the tides
for year for any port takes not more
than IL hours.
In the article on base lines there is
description of the modern method Of
! measurement with tapes of invar met
al now used in the Survey to the ex-
clusion of any other method. The in
var metal is an alloy of nickel and
steel, the advantage of which for this
and many other purposes is that its
rate of expansion and contraction un-
der changes of temperature is about
125 that of steel, so that the i'm
portant source of error due to tempera-
ture changes is practically eliminated.
| The use of tapes has decreased the
cost of base measurement by about 35
per cent. and greatly increased the
rapidity of the werR.
Under the head of astronomy is a
description Of the Talcott method - of
observing latitude by means of which
results of superior accuracy are at
tanned. This method has long been
used by the Survey in precise determi-
nations. The instruments used in the
determination of longitude by the tele-
The use of motor truck for the
transportation of parties engaged in
latitude work is mentioned as having
increased the rapidity and decreased
the cost of such work by large per
cent.
| There are nuemrous illustrations of
instruments and apparatus, parties at
work in the field, etc, and maps show
| ing the extent and character of the
work,
When the survey was begun under
Ferdinand R. Hassler the entire coast
of the United States was on the Allan
tic and Gulf of Mexico. The acquisi-
! tion of California Oregon and Washing
ton, and later of Alaska, Porto Rico,
Hawaii and the Philippine Islands,
greatly extended the scope of the Sur
vey and brought new problems to be
solved. The extension of the triangula-
ton into the interior so as to form a
geodetic connection between the Allan
tic and Pacific coasts; the extension
of this system so as to furnish accurate.
ly located geographic positions and
elevations in all parts of the United
States; and the beginning of syste-
matte magnetic survey of the whole
country, are among the important
works that have been undertaken since
the original plan of Hassler was adopt
ed.
The results of the operations of this
Bureau are of Importance to the navi.
gator, the surveyor, the engineer, and
to all who are interested in works of
public improvement reuiring accurate
! surveys as their basis.
The publication may be obtained
without charge from the Division OF
| Publications, Department of Commerce