The New York herald., 1874-11-30

rim, black, INVISIBLE band seemed to crawl be-
the rims OF both BODIES trembied and struggled,
then there was pause in the planets motion,
when all at once IT was found that Venus had con-
vulslvcy rushed IN to a considerable distance on
the SUMS disc. This same appearance was wit
messed at all the stations, and the observers failed
contact took place, knowledge OF which instant
as We shall see, IS OF paramount importance in
seconds OF time in noting this moment would
cause grave one IN the solar distance, and
yet the observers generally. declared that It
was impossible for them to avoid llabil-
ity to such deviation from accuracy
There was no occasion for despair, however, for
another transit was TO take place IN 1859. In the
meantime the lenses of the telescopes were
changed. the instruments renovated Gorit was to
their defects that the intervention Of the mysteri-
Gus band had been attrbuted) and the expedi-
tlonary forces made ready Tor q fresh attempt.
Wealthy patrons OF science subscribed freely and
cles but extended to the enterprise liberal aid.
The year 1859 circled on and the iong-wlshed day
lore. Venus plided forward, and was nearing the
SUMS edge, when the same confusing band inter-
vened, the appearances OIL l76l were repeated,
fixed within less than twenty seconds OF the &C
tuai time. With such data as they could collect
they made the necessary calculations and, hope
less OF better results dung down their weapons OF
science, leaving the battle 10 be fought again by
their enlightened successors or 1874 rhe estimates
OF uncertainty that they ranged rom 600 TO
los, 100000 OF miles. Subsequent mathematicians
reviewed the various entries and accounts OF the
observers, and finally tne astronomer Encke
scruunized all the estimates. and alter much LABOR
miles. This was accepted BY the entlre scientific
world until few years past, when two strong argu
FoucauIt and fizean. alter series Of ingenious
experiments made at Paris and Versailles, found
that light travels with velocity OF about $4,000
miles per second. Now we know from ODservances
OF the echpses OF Juplter's satellites that light
takes 49s SECONDS to cross from the sun to the
earth, and consequently the solar distance must
measure 49S times lS4, 900 miles, which gives about
nlnety-one and half millions. The second cogent
OBSERVATIONS OF THE PLANET MARS
made In 1862. These observations were made In
order to ascertain the visual. angle presented to
upon pair OF distant stations on the earth, and
to deduce the distance OF Mars from the earth on
the same plans OF determining distances IN gen.
erai as those already explained. 1t must be
borne IN mind that Mars IS about one and half
times as lar as the earth from the sun. and that
sometimes on the same side Of the sun
with ourselves. Such was his location in
M cresnwcn UaDe OF %eie eod Hope
Puikova, santiago and Wihamstown in Australia
The results were found TO agree, and Mars dis
with the suns Will be unfoded little further
At all events the SUMS distance was then esti-
Thus most living astronomers agree within lew
hundred thousand miles as to tue solution OF the
vexed question. Still, the long sought accuracy
has not been arrived at. AL the observations and
estimates or the past hundred years cannot equal
in approach to perfection the methods about TO be
THE COMING TRANSIT OBSERVATIONS,
an elucldation OF which Will now be less dlf1cut OF
comprehension. We have already learned how
ances HIS method we will proceed TO de-
scribe, reminding the reader tnat while no
western strip Of Alaska Will &c surnes
toward the iuminary OF the day during the event.
ml period, the transit wiil be visible to all places
between siberia and the South Pole and between
the middle OF the Pacific ocean and the eastern
portion :. OF Africa. In the northern region
s tract @ b9 o. serr1ps ~ avSa1e %
equipped with clocks that keep exact time; tele.
scopes, Photographic apparatus and Q hundred
Directly south OF this positlon-and distant say
1000 miles therefrom-anotner station Is selected
act In concert with the former. AS seen from the
northern station, the central point OF Venus will
appear 70 move across the suns DISC 10 straight
iine Let us imagine this straight line to be pro-
Jected on the brilliant Disc resembling black
thread stretched across q dazzling silver plate.
To the spectator at the southern station the
planet Will appear higher up on the SUMS disc
and VIII move across In diferent imaginary line
like another black thread stretched parallel TO
ttig. u Illustrates this the northern station on
the earth is at the letter Q, and to an observer
the line MI Tne soussern station IS at D. and
from 'aas point Venus seems TO steal across the
suns disc, Ia the line MM1. The black spots on
the sun resemble the specks OF the SUMS surface
which the planet will conceal rom the respective
observers during It's passage. They seem to be
trife smaller than tue planet itself, and such ac-
suany wi,i @ 1e tne case, owing to deiuson oi tne
than the earth, aud the lines NM and MMi are
stretched further apart than they Will really seem
TO be but all this Is done ior the sake OF cea ness
In the explanation, which becomes more inteligibe
BY reason oil those exaggeratlons In the scale.
The North Pole OF the earth, on the sth OF Decem-
ber will be turned from the sun to an extent that
can be perceived by inspecting the representation
thereof given IN the diagram. AS 70 the
imaginary passage lines across the sun, the
observers cannot see them, but by photograph
Ing the planets position ut several stages OF Its
track, the observers can precisely map them on an
image OF the sun; the observers at the south win
map the line MIMI those at the north the line NM.
Neither band OF observers can tell what track the
planet has presented to the other until they CON-
pare notes. Tnen, however, they can map the two
lines on one photograph. The angular distance
between these tines Is the key to the solution. IL
Will be found TO be the l.S0 of the SUMS
breadth, or the s4-looo part OF a whole
circle. The calculations herein made are based
on the probable distance OF the SUM- and are given
In round numbers Ii. now. we picture TO ourselves
celestial astronomer stationed at Venus, and
looking at the two Imaginary lines MMl aud NM;