Southport telegraph. [volume] (Southport, W.T. [i.e. Kenosha, Wis.]) 1840-1850, 1847-09-08
MORE ABOUT THE TELEGRAPH.

In former articles spoke of the probable in
fuence of the Magnetic Telegraph upon literature,
upon social and political interests and very slightly
OF It's bearings upon science We propose to extend
our remarks under this last head-though, perhaps,
the general reader may not take much interest in
the matter presented The subject, however, is
none the less important for this and ought to be
interesting TO every reader.
The uses of the Telegraph to science are various
and some of them highly important We shall at
present speak particularly only of one. And this
is the accuracy, ease, and certainty with which the
longitude of any place, its distance east west
of given meridian, can be ascertained. This is a
subject which many who pass for we'll informed
well educated persons, have never investigated
Much the greater part probably of those who study
geography, and even of those who attempt to teach
it, can tell nothing about the methods by which
longitude is asceraned and the length in miles
OF degree of longitude at given disence from the
equator. The adage which is made so familiar to
children in the primary school, namely degree
on the earth measures 693 English miles is true
for degrees of longitude only upon or very near the
equator. Within few degrees Of the equator, the
length of degree of longitude decreases in going
north or south at very slow rate. As we depart
from the equator, or advance towards the polar cir
cles, this rate of increase becomes greater ForeX.
ample, at Carriage, in Guatemala, lat. 10 deg, the
length of degree of longitude differs from what it
would be on the equator by less than one mile. At
St Jago on the Island OF Cuba lat 20 the difference
has become more than four miles. AT n Orleans,
lat. 30, the difference has become more than nine
miles At Springfield, Ill, lat 40, the difference
has beaome between fifteen and sixteen miles. At
Liverpool, England, lat. "a, the difference in the
length of degree of longitude from what it is at
the equator, is more than twenty-seven English
miles &c. To calculate and ascertain these differ
ences and to determine accurately the length of de-
grees of longitude for all latltudes problems upon
which the highest order of mathematical talent has
been employed for centuries So important, and at
the same time so difficult was the solution of these
problems, that the British Parliament not hundred
years ago, offered reward of 100000 (almost
100000 to the person who should demonstrate
the true longitude of distant meridian to within
thirty geographic, thirty-fve English miles
The methods most in use for determining longitude
are those employed for ascertaining difference of
time occasoned by departure east or west from
given meridian. If time pieces were perfect, and
there were no difficulty liability to mistake in
ascertanng the true meridian of place, these
methods would be fautless. This however, is not
the case; and furthermore, the purchase of chrono
meters and instruments for observation, requires
considerable outlay to say nothing ofthe knowledge
skill and practise requisite for the successful use of
them Let us look now, at the method of ascer
tanning difference of time by telegraph. Fifteen
degrees of longitude are known to correspond to
one hours difference in time; one degree of ongi-
tude TO four minutes in time; one-iourth of degree
to one minute, &c. Now, for example, if the exact
meridian time of the star be ascertained at
Halifax, and instantly communicated TO St Louis,
and the difference in time is one hour and fftyfour
minutes the difference in longitude between the two
places will be just 233 degrees Thus, ifthe longi-
tude of Halifax were exactly known, that of St |
Louis would be known with equal certainty. The
use of the Telegraph. we see, then, for fixing the
precise locality of places for ascertaining the exact
distance and direction from place TO another,
for knowing accurately than before the extent
of given portion of the earths surface, and for
avoiding errors in the construction of maps and
charts, (Which errors it was next TO impossible to
avoid by the means of attaining accuracy that were
formerly depended on for all these purposes we
say the uses of the Telegraph to the cause of sci
enee will be greaterthan can be easily estimated.
Other purposes of importance scarcely. if at all,
less than those before referred to- may be answered
by the use of the Telegraph. AS for example, a |
multitude Of curious and useful observations upon