The Portland daily press., 1869-03-10

GRAND ELEcTRo-AsTRoNoAuCA EXPERT
MENr.-Ths United States Coast Survey off,
GERS have been engaged for some time past in
making astronomical observations, by the aid
of telegraph, between the cities of the far
West and Cambridge University. For the
purpose OF arriving at the difference in mean
time between San Francisco and Boston, the
wires of the Western Union Telegraph Com
pany have nightly been connected, for nearly
a month past, from one side of the continent
to the other, and the ticking of chronometer
in Cambridge University has been observed
and recorded in San Francisco with most re-
markable degree of accuracy.
This is done by connecting the pendulum
of the chronometer at Cambridge with the
wire, in such a manner that the main circuit
is broken, and instantly closed again at every
beat or tick of the time piece, and the result is
that each second of time as marked by the
chronometer at Cambridge, goes forth from
the University on the Atlantic coast, and,
with almost the speed of light itself, hurries
ON over the magic wire, passing through inter-
mediate cities, towns, and villages, across riv-
ers, over mountains, and along the open coun-
try, until it finally reaches the recording in
strument on the Pacific coast in all its original
fullness of pulsation.
At any time during an evening of the past
month, . visitor to the operating rooms of the
Western Union Telegraph Office, might have
heard one of the little instruments beating the
measured time Of the sixtieth part of minute,
with the monotony and regularity of chro-
nometer ITSELF Tick! Ticki Ticfi One. two.
three four ue minutes elapse, and then the little
monitor ceases. Back comes the answer from
San Francisco to Boston: All right; your
second signals come good and have been re-
r1olf nr min 10 oh Avo mil 1kao
more" Again, tick! ticki tick! for five min
utes, and then San Francisco says again: All
right; are you ready to take my signals?"
And the answer from Boston is, Yes; go
ahead" Tick! Tcki Tick! says San Francis.
co for the allotted five minutes, and Boston
says, in his turn: All right
But notwithstanding the speed with which
these pulsations of clock fly from one side
of our continent to the other, it is known
that there is a loss, a very slight loss, of
at this loss, and measure 1t, is the next
question. Nothing easier; second wire is
switched into place, a repeater" added at
Boston, and, prestoi tits done. Now the clock
of light, over the 5000 miles of wire to Boston,
and back again to San Francisco over the Sec
ond wire, and record themselves at the point
of starting, in something less than 60 Sec
onds of time, having, in the interval, ira
versed 5000 miles. Last Monday night wit
messed the successful completion of this last
experiment, and the flight of electricity was
actually measured, SO to speak, as easily as
one measures yard of muslin. Never before
in the worlds history has such wonderful
feat been attempted.
The route is from Boston through Albany,
Buffalo, Detroit, Chicago, Omaha, Cheyenne, Salt
Lake City, and Virginid City to San Francisco
and this route is OF course doubled, forming,
for all practical purposes but single circuit.
The places in italics above, indicate where re-
peaters are used to form the double circuit