Sacramento daily record-union., 1881-11-08
THE TRANSIT OF MERCURY.

When either Of the planets revolving within
the orbi. Of the earth passes SO near to line
drawn from the sun to our globe as to appear
projected upon the disc of The former, 8 tran
sit Of that planet is said to take place. Inc
tranaits of Mercury are of more frequent oc-
currence than those Of Venus, though CT lar
less astronomical Importance. In this cen
tury Mercury has passed across the disc OF
the sun on these dates: November 9, 1862,
| from lust below ecliptic, crossing it at one
third It's diameter and passing off above it at
an angle Of about fifteen degrees. November
I2. 1915, across the upper fifth of the suns
disc, at about the same angle. November 5,
1922, across the lower sixth of the suns disc,
at about the same Single. May 5, 1882, across
the suns upper quarter, ct downward angle
of like inclination. November z, 1885, across
the lower third at al upward inclination Of
abont15 degrees. May s, 1916, across the lower
fourth OF the diameter of the Gisc and par
allel with that of 1882 November 9, 1S4S,
starting just above the eclip.ic at the first
point of contact, and passing upward at an
inclination Of about Is degrees. November
II, 1851, parallel with that of 1915, and just
above it. November 5, 1868, parallel with
that OF 1922, and just above it. May 6, 1878,
P~4oA4CA Win etldb VI lCO-, anu DctOh IL az 2
distance equal to about one-ninth of the di-
ameter of the SUMS disc. Anyone by draw
ing perfect circle, cutting it in half by a
line to be marked the ecliptic, and noting
these lines OF transit with ruler and pen
cil, can get comparatively clear idea of the
direction Of the planet across the suns disc
during this century. Yesterday there was
another transit, and it was parallel with that
of 1885 and Just above it, or, in other words,
it crossed the disc Of the sun below the eclip-
tic at an upward inclination of about 10 de-
grees, and crossing in line which would
divide the disc into considerably more
than one-third but less than one-halt its
diameter. The astronomical prediction of
latest date was that the least distances OF
centers would be 23l.1 Of an arc, or about
10 of the suns angular diameter. An OBJ
servation was made by attaches OF this office
with Richard Dale's telescope, and the planet
discerned, but the situation was not suf-
fciently elevated or convenient and the re-
suits hardly as satisfactory as those had from
the Capitol with an astronomical telescope OF
23-inca aperture and nagnifying eighty
times. The observation was made by Major
Bender and party of gentlemen embrac-
ing General Shanklin, Signal Service
Officer Berwick. a. L. Goddard, Rev. n.
Slater, r. o. Crayens, Mr.. Stratton aud
others. The air was very clear, and the
planet was very sharply defined as round
black spot, q perfect sphere, from 2h. SIN. to
sunset. Some solar spots were also very
clearly seen. Apparently the planet, to these
observers, passed within quarter of the
radius of the sun from the center at about
4h. 46m, or little before sunset, SO that to
have seen the whole transit an oS-
server must have been little fur.
ther west than the Sandwich Islands.
The next transit of Mercury will occur May
9, 1891, and the last in this century Novem-
ber 10, 1894 The first of these will be
parallel with that of 1915, and below it,
and the last parallel with that Of 184S and
just above it. The value OF accurate obser
vations of the transit of Mercury, as taken
with powerful instruments, resides in the fact
that the planet is so near the sun and so en-
tangled in the mark of the horizon, that
neither its shape nor angular measurement
can be determinend in ordinary observations
with desirable accuracy. But when the
planet crosses the disc of the san it appears as
a clear-cut black spot upon the brilliant back
ground of the sun, and then it may be studied
to much advantage. As Professors Holden
and Burnham, of the Madison observatory,
took observations yesterday at Mount Ham
ilton, Santa Clara county, the astronomical
and accurate results will soon be learned.