The daily union. [volume] (Washington [D.C.]) 1845-1857, 1847-09-02
From the New York Journal OF Commerce
Longitude of New York City by Magnetic Telegraph.


difference of longitude between New York, Philade
phia, and Washington, by means Of the magnetic ele
graph We understand that these experiments have been
and have been brought TO successful con
cuson The observations at the Washington Oh
servatory were made by Professor Keith those a
Philadelphia by Mr. $, c. Walker and those al
were connected by continuous wire so that telegraph
ic signals might be exchanged between any two OF them
at pleasure. In some of the first experiments signals
We're exchanged between Jersey city and Philadelphia,
and also between Philadelphia and Washington; but
found impossible 10 transmit signals directly from
Jersey city TO Washington. The power OF the battery
appeared inadequate that distance But on the 29th OF
July this difficulty overcome. Twenty clock sig
nails given at Jersey city, and recorded both at
Philadelphia and Washington; twenty signals were
given Philadelphia which received al Jersey city
and Washington; and twenty signals given at Washing
ton, received at Jersey city and Philadelphia Thus
the comparison of the three clocks perfect and thus
the original plan of observation fully carried out
This glorious success, and enough TO repay the OBJ
servers for all their past dsappoInimens. The same
complete set of signals has since been again exchanged
between the three Observaores The object OF the OBJ
servations has thus been completely attained
The difference of longitude between Jersey city and
Philadelphia is four minutes and thirty seconds; and
between Jersey city and Washington, tore minutes and
three sscondomitlng in each case attraction OF second
which only be fully determined when all the obser-
vations have been completely reduced
1t is not to hear doubts expressed respect
ing the enormous velocity which ascrbed to the trans
mission of teegnphc signals The experiments Just no
tced afford information upon this point They FUR
ns The means OF measuring the velocity OF te eleCuiC
fluid sprovded the time employed in its passage from
Jersey city TO Washington is not too small to be appe-
cated Suppose the difference of longitude betweeh the
two places is exactly twelve minutes. Accordingly
when it is ten O'Clock at Washington, it will be twelve
minutes past ten at Jersey city, let now
signal be given from Jersey city Ii that signal IS heard
at the same instant at Washington, then the Washington
clock should indicate exactly ten hours But # 1t re-
qures second for the signal to travel TO washington
then, upon its arrival, the Washington clock VIII md
cate ten hours and one second that Isl according to this
the difference between the JERSEY cltV and
Washington clocks will appear to be etereh minutes ana
tynine seconds Suppose, again, that at ten O'Clock
signal given from Washington. Ii that signal is heard
at the instant at Jersey city, then the Jersey city
clock should indicate exactly twelve minutes past ten
but if it requires second for the signal to travel from
Washington to jersey city, then, upon its arrival, toe
Jersey city clock should indicate hours twelve min
utes and second; that is according TO this compar-
son. the difference between the two clocks appears TO be
ticeite minutes and one second. The two comparisons
differ by tco seconds twice the time required for the
signal to travel from Jersey city to Washington Now,
whatever may be the time required for the TRANSMISSION OF
signal the difference between the two modes OF compar
ing the clocks should amount tcce this interval and
the longitude derived from signals transmitted from Jer
sey city Washington should be less than that derived
from signals transmitted from Washington to Jersey city
What now is the result of the experiments actually
made The longitudes derived from the two modes OF
comparing the clocks do really differ; The dterence
amounts an some cases, TO One-ltrd Of second But
strange as may appear this difference is IN the Drong
direction The longitude derived from signals trans
mited from Jersey city to Washington is greater than
that derived from signals w
to Jersey city The conclusion seems to follow, that
elegraphic signal is transmitted than two hun
dred miles in less than time. Observe, that we now
speak of absolute not local time; Tor 1t Is not doubted
that signal made at Jersey city at ten o'clock, Will
reach Washington long before ten, according to Wash
ngton time But the observations to indicate that
signal from Jeey city is heard at Washington before
Is made at Jersey city and also, that signal IRON
Washington is heard at Jersey city before At IS ndde
at Washington. Such conclusion will suit poetry
better than science 1t seems probable that the dii-
ference in question arises from the difficulty OF esna
ting minute fractions OF second This is indicated by
the fact that, evening, the Jersey city and Phila-
depha clocks were found TO tick together and the SIG
nails being given concident with the beats OF one clock
the times of arrival conceded with the beats OF the
other clock. Thus there wasTno fraction OF second
for the TO estimate, and the two modes OF comPar
ing the clocks gave Identical results On several even
ngs the discrepancy in the observations amounted 10
about oaehd Of second and If we suppose each OBJ
server to err his estimates by oneSir Of second, the
difference is explained; only must admit that each
observer, upon the arrival of clock sgna estimates
the time sixth OF second too soon; which seems
to indicate that the signal is heard at distant station
before ii is really made.
That this hypothesis is not without Foundations mas
been verified in the following manner The ihree OBJ,
servers Messrs Loomis, Walker and Keith, have met
Jersey city, and compared their methods OF observation
especially their modes OF estimating fractions OF a
second This was done by comparing solar tune wltn
than the sidereal and sidereal clock VIII therefore
gain upon a solar clock second IN about SIX minutes
series of signals was transmitted from Jersey city to
Philadelphia intervals of ten seconds, colnclden with
the beats of solar clock, and the times recorded by fro
lessor Kendall at Philadelphia upon sldereal clock
The times also recorded at Jersey city by sdereal
clock These signals continued Tor ten minutes;
durihr which time the sidereal clock had gained more
than one second upon the solar The signals being all
given concident with the beats OF solar clock the ac-
ons second estimated upon the sdereal Clock go on
continually increasing and pass through every possible
value in about six minutes In period OF ten minutes,
the clock beats must twice coincide Now the ear can
Judge of coincidence of beats with almost absolute pre-
cision and having determined the nsants when the
beats coincide easily compute what fraction ought
to have been estimated upon the sidereal clock at each
signal from the solar clock Thus obtain the error OF
each estimate OF time upon the sderea clock "A similar sci
of signals given at Philadelphia from solar clock and
received at Jersey city upon sdereal clock ne result
of these trials TO detect small error In the estimation
of fractions of second and such will explain IN part,
if not wholly the discrepancy of the observations
One important conclusion is deduclbe from these eX-
perments viz that by means of the magnetic telegraph,
clock in New York be compared nth another at a
clocks can be compared adjoining rooms Another
conclusion which appears to be authorized by these ex-
perments is, that the time required for the electric fd TO
travel from NeW York to Washington and back dgdtnd
distance of $50 miieSis so small fraction Of second
that 1t IS inapprecdbe to the mos, practiSed Observer
To Pursers and Surgeons Of the U. $. Navy.
TIME subscribers received from London (nade
to order by one of the first manufacturers) epauetles
for all grades according to the recent order oil ne Navy
Department; also shoulder-sraps (which they offer at the
lowest p'S''''' p''''' VIM II. sM! I'll 81 CO.,
l. Aup 7-Im* No. Maiden La lie, New York.
Marshal's Sale.
TN virte of writ of Eeri acias acias under the