The daily union. [volume] (Washington [D.C.]) 1845-1857, 1847-09-14

the longltudes OF different places which the telegraph
was extended We struck by the ingenuity OF thu
process stated il in article which prepared Tor The
Union and promised further development OF the re-
suits which it might produce We advised at the
time TO apply for further information to A. D. Bache esq
the accomplished superintendent of the coast survey
But the mperection of insulation in the wires and Other
causes prevented at that time the full which
anticipated and its consequent explanation The results
of the elegabhic operation for differences of longitude
between Washington and New York. connected with the
coast survey, having proved altogether successful we
have now the satisfaction of laying the following very
interesting paper upon that subject before readers
We recommend it, al the time, to the astronomers
and engineers beyond the Atlantic
| DIFFERENCE OF LONGITUDE BY TELEGRAPH.
One OF the earliest uses OF Morses Electro mag
netic Telegraph was that OF determining geographical
longitude. few signals passed between Wash
ngton and Baltimore in 1884, under the direction of Capt
Wilkes, by carrying chronomcters from astronomical
stations to the telegraph Offices But the most complete
trial OF tins method extant has recently been made under
ne direction OF Inc present superintendent OF the United
States coast survey, Professor Bache
In the autumn of 1915, arrangements were commenced
TOR making an experiment on the whole extent of the
line from Jersey City to Washington, a distance of $50
1916, trials made. The violent storms of the au
umn and the continual repairs along these new lines
prevented complete success in 1916 Accordingly, in the
months of July and August of this year, operations were
resumed on the new and more perfectly insulated lines
Professor Bache had built, at the expense OF the sur
vey, line from the Washington post office to the Ma
onal Observatory lie had procured for the three OBJ
servaories of Washington Philadelphia and Jersey City,
ull and complete telegraph apparatus and had connected
them with the main line, to make these Observable
temporary telegraph Offices having rented the line of
The Telegraph Company for astronomical purposes only
Professor Bache had ao at toe expense of the survey
erected the temporary observatory at Jersey City, and
afraIth n Of
gushed director of the Western Reserve Observatory now
IN the char of physics in the New York University He
had also engaged the services OF Professor Kendall the
director of the observatory of the Central High School of
Philadelphia. Lieutenant Maury, the superintendent of
The National Observatory had early in 1915 rendered to
Professor bache the operation OF that establishment
The arrangement OF the details of the work ntrust
ed to Sears C. Walker of the assistants of the sur
vey 1t is understood that full and detailed report of
these operations will be made this autumn by the super
lntendent to the Secretary OF the Treasury AS par
tla notices OF the work have already found their way
prematurey into the public prints, authorized to
lay before our readers IN an authentic form, general
view OF the nature OF these operations, OF which the
suits will, IN proper time, be made public.
The clocks at the observatories having been carefully
regulated by astronomical observations, at 10 p. pos
session of the line for the night is given over to the as
tronomers and sklu operators accompany them each
station.
The performances of the Sd of August, 1s47. NAV be
quoted as an example OF a successful nights work.
The source OF electrical power Groves constant
battery having ory-four half-pnt cups. The magnets
were by the operators, ana twenty CLOCK signals
were gwen by Mr. Lanznger, the operator at Jersey
CITY, at intervals oil ten seconds EACH and at condolences
with the clock beats. These twenty signals were com
pared with the Jersey City clock BY Professor LOOMS,
Jersey City.) The twenty were received and com.
pared with the clock OF the Philadelphia observatory by
three observers Messrs Walker Reynolds, and Mason
professor Kendall being abscnt) The of TWEEN
" signals also received and compared with the clock
at the Washington observatory by Professor Keith the
officer charged with this duty by Lieutenant Maury
j.
phia and from Washington recorded at the three
stations. 1t is known that no two observers, with the
transit instrument and clock obtain for the same
correction. Each has his peculiar habit OF seeing and
hearing became necessary for all the observers to
meet together and to make observations at the same
place. the evening, with the same instruments,
order to find the reduction of each clock
ton to normal or average value.
After applying this correction for the pecuarties of
the observers, it may be presumed, from the excellence
OF the instruments and experience OF the Observers that
he corrected clocks at Washington Philadelphia, and
Jersey City, indicated the true sdera time of these merd
ans, within quarler--perhaps within tenth partof
second.
The method adopted of observing zenith stars before
and after reversal of the transit instrument, gives to the
clock time, after correcting for personal equations pre-
cson little short of the actual leveng Now with the
levels in use at these places, second OF arc seventy
feet OF longitude, represented by line tenth of
inch The precision OF full nights work may be readily
reduced within forty feet SO far as the leveng nstru
ment IS concerned.
If these clocks or chronomeers so corrected could be
notions simple comparison of their corrected readings
for the instant of time wonld give the difference of
longitude with precision not far short of the clock
rectons themselves, of the levelng observations on
which they chiefly depend This method forms the basis
OF the chonomeer expeditions, of which extensive and
successful made by Robert Treat Pane, esq.,
the Massachusetts survey.
It'll in the that the observatories of
Liverpool, England and of Cambridge, New England,
have been connected together by VIM. Cranch Bond.
esq, by means of the chronometers of the Liverpool
steamers
transportation of chronomeers and only transports the
essential portion, viz the clock beat itself.
The practised observer readily strike his key
with such precision that the most delicate cannot dis
tngush any of accord between the clock beats and
the key beats This method of beating time resembles
the process of the leader of an orchestra.
SO far, then, the giving of signals s concerned no
error need be apprehendei But the party who at an
other observatory, receives this signal and enters the
clock time of IT, according TO the best of his Judgment is
liable to three separate and independent of
The first is in the time Gf any employed by the cleo
tromagnetc fluid, or wave, in aversng, Tor instance,
the two hundred and fifty miles OF the wire that connects
the Washington and Jersey City observatories
The second is the time that elapses after the fluid or
wave has raversed the interval and commenced the in
ducon of magnetic action in the receiving magnet, and
before it brings up the anatre and causes an armaure
beat that is recorded by the receiving observer.
The third is the Coramitted by the receiving OBJ
in noting the fraction OF second between the
clock beats preceding and following his amature beat.
From this enumeration oil the of error, IT APP
pears that when take the OF the two values Tor
the longitude between Two observaores by the eastern
and the tCeen Signals the result requires four correc
tons one IS Tor the difference personal equation, OF
the clock eorreet,on for that of clock aongs
third Tor that OF circuit time, (astronomcay, 0berd
han ~ mil l,,rt tbr4a