The Hickman courier. [volume] (Hickman, Ky.) 1859-current, 1882-07-14
CaIeuIatIng Longi!ua,.

To determine the difference of lopgi-
'tude between two places it is only
necessary to fir.d the differenc. of their
local times; but. simple as this may
appear. without the aid of the tele-.
graph it is one OF the most diiliculB
lsfe3lemss Of practical -. -.
the dawn of the seVentethth centurx
chronometers were unknown, and the
world was destitute OF any mechani-
cal means OF transmitting or transport
ing the local time of one place to an
-other. The mooR's motion was not
available because the lunar theory was
too Imperfect to admit 1of satisfactory
Predictions of the moon's place.
Eclipses4 of Jupiter's satellites were
even more unavailable, because tele-
scopes had not boon iuventeds and no
man knew that the. satellites existed.
: .AlInest the only possible -rnethod of
operating WAS by actually measuring
4he, bearing. and distance between the
places whose differences OF longitude
was required. But here again very
great difficulties were encountered.
The figure and size of the earth were
but impeisectlv known and he instra-
ments and methods of eeoeesy had not
| been rinventeu. sinssliort, The astfono-
unefsl and ecographers of that time had
fewresources beyond the linear measa
urement Of eroutes actually trfversed
from place to place No wonder their
maps were Inere car catures. Think
.oiIrYing1o measure tile distance across
4heA ttantic in that way, even with the
taitlaof patent logs used on board White
Star steamers Yet that was what
Columbus had to do on his poor littIe
Ships, without the patent logs, and the
result is that the identity of the island
upon which he first landed is even vet
asu5icct OF dispute. Few. persons real
ize the amount of Uncertainty exist
ing in the ordinary rough measure
fncnts of everyday lie An error of
lone part in a hundred Corresponds to
less than three-eighths-. -.sf an zach in a
/ yard. aHd7 there are 9 few .drx-yoods 3
stores where eYtn the most. ,expeDsiye
silks are measured more carefully than
that's An error of one part III athousand
I Corresponds to about five feet ins a mile.
4 and the country surveyor seldom works
that accurately. An error of one, part
in ten thousand corresponds to less
/ than mile in the 0iaEeter of the earth.
and to attain such sxactness the utmost
kcare of the best engineers is needS
Eo, makeesure of committing no =
+ greater than one part in one tho
requires the most lavishsexpends
time and the use of, the best
ments by scientific men of the h
/ ability An accuracy of one part
million can-but rarely he attained, ev
under exeeptienalE favprabEe circurn.
stances. The maps of Columbus time
were made from itineraries-th is,
/ from distances measured along the
lines of travel. few of which were
known any thing like so accurately as
I one part in a thousand. AS the. direc-
/ tions were still less exact the maps were
necessarily grossly erroneous.
/ The earth is our great timepiece
whose steady revolution causes the sun
/ to rise and set, and gives us day and
! night. But owing to the vast size ot
/ the world and our relation to its surface
we fail to realize that it is in rapid ro
/ tation, and thus we COME to regard the
apparent motion of the sun as real, anc
we regulate our time by it. The heav'
ems are stO-us an immense dial and the
sun is the hand which indicates ths
time upon it.-N. ]. Herald
IAN extraordinary tricycle. journey