Weekly national intelligencer. [volume] (Washington [D.C.]) 1841-1869, 1847-08-21


washington by meas of the Magnetic Telegraph. We
uefsahd hat those experiments have been continued and
nave oeen brought to successful conclusion The obseva
ons al the washington Observatory made by Professor
hei'h those at Philadelphia by Mr.. S. C. Walker and
those at Jersey City by Professor LOOMS These three OBJ
servaoes connected by continuous wire SO that tee
graphic signals might be exchanged between any two of them
at pleasure In some Of the first experiments signals were
exchanged between Jersey City and PHILADELPHIA and also
between Philadelphia and Washington but il was found i'm
possible to transmit signals directly from Jersey CITY to Wash
ngon The Of the battery appeared inadequate to that
distance. But the Goth of July this difficulty was over
come Twenty clock signals given at Jersey City, and
recorded both at Philadelphia and Washington twenty sig
nails given Philadelphia which received at Jersey
City and Washington and twenty signals given at Wash
Ington were received Jersey City and Philadelphia Thus
the comparison Of the three clocks perfect and thus the
original plan OF observation fully carried out This was
glorious success and enough repay the observers all their
past disappointmens The complete of signals has
since been again exchanged between the three Observaores
he object OF the observations has thus been completely at
tanned.
The difference of longitude between Jersey CITY and pba
delphia is four minutes and thirty seconds and between
Jersey City and Warrington tUepe minutes and three Sc
cod omtng IN each case fraction of second, which can
only be fully determined when all the observations have bee
comPiessly reduced.
is not uncommon hear donrs expressed res,.c. tho
enormous velocity which ascbed the transmission Of tel
CBidPuiC sSHds ne experiments noticed afford
information upon this point They furnish the means Of
measuring the velocity of the electric fluid provided the time
employed IN its passage from Jersey City Washington is not
TOO small to be appreciated Suppose the difference of onp
uae between Inc TWO places is exactly twelve minutes Ac
cordingly, when is ten o'clock at Washington il will he
twelve minutes past ten at Jersey City, Let now teepraph
signal be given from Jersey City, IF that signal IS heard at
the same instant at Washington then the Washington clock
should indicate exactly ten hours But if it reaues one Sc
cond for the signal travel Washington then upon its ar
rival the Washington clock will indicate ten hours and one
second that Is according this comparison the difference
between the Jersey City and Washington clocks will appear
to be eeuen minutes and tynne seconds Suppose again.
that at ten o'clock signal is given from WASHINGTON r.
that signal heard the at Jersey City, then
the Jersey City clock should indicate exactly twelve minutes
past ten but requires second for the signal to travel
from Washington to Jersey City, them upon its arrival the
Jersey City clock should indicate ten hours twelve minutes
and one second that is according this comparison the DIFF
terence between the two clocks appears be tee minutes
ana one second The two comparisons differ by seconds
or twice the time required for the signal travel from JERSEY
City to Washington. Now whatever NAV be the time re-
CURED for the transmission signal the difference between
the two modes Of comparing the clocks should amount to thrice
this interval and the longitude derived from signals trans
mited from Jersey City to Washington should be less than
that derived from signals transmitted from Washington to Jer
sey City.
What now, is the result of the experiments actually made
Inc ongudes derived from the two modes of comparing
clocks do really differ. The difference amounts in some
cases. TO one-trd OF second But strange as il may APP
pear this difference is IN the rong direction The longitude
derived from signals transmitted from Jersey City Wash
ngon is greater than that derived from signals transmitted
from Washngton to Jersey City. The conclusion seems to
follow that teegraphc signal transmitted more than two
hundred miles IN less than time. Observe that we now
speak of absolute not local time it is not doubted that
signal made at Jersey City o'clock will reach Washing
ton long before ten, according Washington time But the
observations TO indicate that signal from JERSEY Civ
is heard at Washington before is made at Jersey City and
also that signal from Washington heard at Jersey CITY
before ii as made at Washington Such conclusion will
,Io N,otb he
difference in question arises from the difficulty of estimating
minute fractions of second This indicated by the fact
that on one evening" the Jersey City and Philadelphia clocks
were found to tick together and the signals being given COIN
cident with the beats Of clock the times OF arrival coin
cded with the beats of the other clock Thus there was no
fraction of second for the estimate the two modes
OF comparing the clocks gave identical results On several
evenings the discrepancy the observations amounted to
about 0ethd Of second and if suppose each observer
to err in his estimates by oesi Of second the difference
explained only we must admit that each observer upon
the arrival Of clock signal estimates the time one-sixh of
second too which indicate that the signal is
heard at distant station before it is really made
That this hypothesis is not without foundation has been
verified IN the following manner. The three Observers
Messrs LOOMS, Walker and Keith have met at JERSEY city,
and compared their methods of observation more espec,y
their modes of estimating fractions of second This was
done by comparing solar time with sdeea time The solar
day about four minutes longer than the siderea and 81
deeal clock will therefore gain upon solar clock second
about six minutes series of signals was transmitted
from Jersey city TO Philadelphia intervals Of ten seconds
concden with the beats of solar clock and the times re-
corded by Professor Kendall Philadelphia upon siderea
clock The times also recorded at Jersey CITY by side
real clock. These signals continued for ten minutes
during which time the siderea clock had gained more than
second upon the solar The signals being all given coin
cden with the beats of solar clock the fractions of second
estimated upon the derea clock go on continually nceas
ing and pass through every possible value in about six minutes
In period of ten minutes the must twice coincide
Now, the judge OF coincidence of beats with almost
absolute precision and having determined the nstants when
the beats coincide easily compute what fraction ought
to have been estimated upon the derea clock at each signal
from the solar clock Thus obtain the error of each est
of time upon the seea clock similar set Of signals
was given at Philadelphia from solar clock and received at
Jersey city upon sderea clock The result of these trials
to detect small 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 deducble from these expert
ments, viz that by means Of the magnetic telegraph, clock
IN NW York be compared ,ch another al distance of
t'co hundred miles quite accurately too clocks be
compared IN adjoining Another conclusion which
appears to be authorized by these experiments is that the
time required for the electric fluid TO fravei from No York
10 Washington and back again, distance Of four hundred
and my miles, is small fraction ofa second that is
inappreciabh 10 the most practiSed Observer.
The TELEGRAPH.-ExTRAoRDISAR INFLUENCE OF THE
FLuID-We deem it duty to state the following facts
that they by the of caution to readers
against touching using any the poles Of the Te
legraph. horse and wagon proceeding down the