The Republican journal., 1874-08-06
FOR GOVERNOR
Joseph Titcomb,
Among the Planets.
OF KENNEBUNk

Among the Planets.
The next important event OF the vlS
BILE heavens, now that the comet has van
ished from our morta! gaze, is to he grea
transit, when our next neighhor in th(
| planetary SYSTEM the queenly Venus, vii
sail across the burning face Of the sun
This will occur in December, and will bC
the great astronomical event Of the cen
tury. The New York Herald chronicles
the preparations made to observe the phe
nonenop. The United States, by the con
fession OF all. has most largely embarked
in this high scientific cmprisc, and he1
observers will occupy stations the most
difficult of access and least pleasant Of
tenure, but most promising Of rich re-
suits, both in the Northern and Southern
Hemisphere. These stations are dlstri-
| buted. three in the Northern and five in
the Southern Hemisphere, and selected q
suitable for observing the entire passage
OF Venus across the suns face Russia =
corps o1 observer Is next in importance,
and though their stations are to be all
within Russian territory the field Will be
ample for the most satisfactory research.
The English will have seven parties at
work, the Germans AT least four and the
French five or, possibly. six.
Il, 1 l.
national cooperative work it is necessary
to note the progress made i'll transit ob2er-
vations since 1859, when the famous Jere-
miah Horrocks and his friend Crahtree
witnessed the first transit which astronomy
had predicted. The prime object Of the
transit observation is 10 determine the ey-
act distance Of Venus from the earth,
since in the determination of this distance
are wrapped up the solutions Of the several
important problems Of solar astronomy 50
long sought after by science, There arc
four methods devised tor obtaining Inc
tact that Venus as seen from different ter
restrial viewpoints at any instant of her
transit will appear projected on different
parts OF the suns face. If two widely
separated observers should at the same in
slant find the exact apparent place OF
Venus on the suns face, comparison of
observations would show how much the
star was displaced in direction, and the
distance between the observers being
known and serving as a base-line, the re-
CURED distance Of Venus from the earth
is easily calculated This is the direct
method Of transit observation
But the nicely required in measuring
the distance between the two observers
and the difficulty of obtaining it in the
last century led HALEY to devise another
This famous scientist proposed that two
/ observers, one at northern aud the other
at a southern station, should note the
exact time the Star consumes in complet-
| ing lis transit across the suns face, along
/ the two different paths she will seem Gas
viewed by then) to follow, and thence to
deduct the length OF these two apparent
paths, which affords the very displace-
ment of the star required This method
is dependent for success on conditions
which make the entire transit visible
conditions hard to realize, since barring
cloudy weather, the transit lasts several
hours, and the axial whirl Of the earth
may take one or both observers out Of DO
sition to see the whole transit The De
Isle method aims to escape the contin
gencies which jeopardize the success 0
the Halleyan method, by simDlit ing thu
observations to the determination of thu
moment when, from opposite sides Of thu
globe, the transit is seen to begin earlies
and to begin latest. If one station OBJ
serves when the transit begins first ano
another at the opposite side of the eartl
notes when 1t begins latest, a comparison
Of records affords the data for computing
the distance of Venus from the earth, ant
thus. consequently, of ascertaining thu
exact distance of the sun But to pu
this method into successful operation
each observer must have previously as
certaiued with great exactness his longi
tude and also his local time. which ar
hard to obtain, and make the Dclisleal
method somewhat precarious. The last
or Photographic method, consists in max
ing the sun picture his own disc, witt
Venus On the face, at any instant, whicl
furnishes data for q comparison simila
to that obtained, but without photo
graphy, by the direct method,
The American observers will rely main
, ly on the Halleyan and photograph
methods, but not to the exclusion of bot
the others. The Russians will employ tn
i. Halleyan method in their most importan
, expeditions, and the English the Delislea
and Halleyan. The French will combin
the Halleyan with the Photographic ap
, paratus, and have already prepared 70
very extensive observations 1t is preit
well agreed upon that, of all the method
to be employed the Photographic has t
contend with the fcwest difficulties, an
the value of its results will be largely or
!, HANGED by the fact that the actual meas
: urcments will be made after the transit
when the excitement of the observer ha
cooled down.
Apart from the calculation Of man
: other practical problems, the success c