The Portland daily press. [volume] (Portland, Me.) 1862-1921, 1867-01-25

A correspondent Of the Boston Transcript
furnishes the following very interesting ac-
count of the progress OF the United States
Coast Survey in determining the difference in
longitude between England and America by
the American or telegraphic method, that is.
by noting the transit ofa star at two telegraph
ic stations and observing accurately the differ
ence of time: up l4a H.
Though the importance of the submarine
telegraph across the Atlantic is chiefly felt
commercially, there are other and very inter
esting uses to which it may be put. One OF
these is the determination OF the difference OF
geographical longitude between the New and
the Old Worlds. INV es.f
The telegraphic method Of determining longi-
tudes lar surpasses all others in the accuracy
of its results Its inception is due to s. &.
Walker OF the U. S. Coast Survey, but its full
development in the fofm which is now en-
ployed in the Coast Survey is the work of DR.
b. A. Gould OF Cambridge, who. everything
considered, stands undoubtedly at the head Of
American astronomical science
During the past fifteen or twenty ye,rs. the
coast survey has determined by this method
the Longitude differences of series of points
in the United States, with an exactness far
SURPRISING what has ever been attained ON the
other side OF the Atlantic Indeed. i'm all
WORK OF TINS KIND Europeans seem to have met
with singularly poor success.
The difference of longitude between Eng
land and America has hitherto rested upon
the chronometric expeditions instituted by the
Coast Survey during the years 1S49-51 and
1900. Fifty chronometers were transported
between Liverpool, England, and Cambridge,
Mass, three times in each direction across
the Atlantic. The probable error of the re-
suit by these expeditions was nineteen-hun-
dredths ola second. The value thus obtained.
though for all practical purposes sufficiently
precise, Is NOT SO ior the necessities OF astron-
Omlcal science in its present refined state
When, therefore, the success of the cable nro-
vided telegraphic transatlantic connection
with England, parties of the Coast SURVEY
were formed under the direction of DIR. b. a.
Gould, TO take advantage OF this means of OBJ
tanning value more precise than that fur
nished by the chronometric expeditions, allu-
sion TO which has been made.
The pecuiarities in the methods, and an
paratus employed in working the cable, render
the process OF determining longitude by its
means dillerent I'D many respects from that
by the land telegraph lines. New obstacles,
which made success exceedingly doubtful,
were to be surmOunted, and new sources Of
error eliminated. But thanks to the genius.
experience and perseverance Of DIR. Gould
these have been overcome, and results of re-
markable precision elected. The probable
error OF the resulting longitude is about four
hundredths OF second. Perhaps it will give
the reader clearer idea of the nicety i'm
piled in this, by stating that distance of
about nineteen hundred miles has been
measured, and that the measure is not proba-
bly, more than forty feet from the truth.
The time required for a SIGNAL to mass
through the cable has been discovered with
still greater precision to be thirty-one hun
dredths OF second; which is probably not in
error by one hundredth of second
This is equivalent to velocity of six thous-
and and twenty miles second, and is notably
less than the velocity of the electric fluid upoI,
land lines which numerous observations have
shown 10 average sixteen thousand miles IN a
second.
1t should be matter of national pride that
Americans have obtained the precedence I'm a
work OF such importance. This Importance
will perhaps be more popularity appreciated
from the fact that this longitude determina-
tion was fully determined upon, and partially
prepared for, by the English, and seriously
contemplated by the French, when Ameri.
cans, with characteristic vvacity, stepped in
and bore away the prize. =