The Democratic press. [volume] (Ravenna, O. [Ohio]) 1868-1901, 1874-07-16
THE COMET AND rHE EARrH.

THE COMET AND THE EARTH.
Ne Shall Narrowly Escape Contact with
the Tail--Result of the Latest Obserya-
tions and CaleuIations.
To dhe Editor Of the Tribune.
SIN: Since writing my eommuni-
cation to The Tribune of July 4, 7
have satisfied myself that the delay of
be about four days, during which time
the earth will have moved so far that
no probable error of computation or
OF estimation would bring US within
it. Having settled that point, shall
introduce an illustration which other
wise might have been too suggestive
of danger. A tall man, having an in
dia-rubber club two feet long, and
three inches in diameter at the end,
sees a spider running very rapidly
across the table. He raises his club
aloft at arms's length, and brings it
down with a terrific blow. He aims
for point two feet in advance of the
spider, so as to allow for its motion,
and strikes very nearly the point
where the spider would have reached
when the club struck The table; but in
consequence of the club bending a
little more than he anticipated, the
spider escaping by one inch. This is
an approximate representation on q
small scale, of what will take place
within the next three weeks, with
two exceptions. In the first place the
club, instead of being of rubber, is of
such attenuated material that if the
spider were hit he would not know it
and secondly, an ordinary spider
would be many thousand times too
large to represent the earth. Perhaps
[ should add third, that the size OF
the club is only known from estimates,
since it may increase in thickness dur
ing the blow.
On July Sd I estimated the length
of The tail of the comet to be IL deg,
but the end of it was so faint that
many persons saw it not more than
half that distance. On July 5th / es-
timated the length to be II deg, and
a company of persons with me varied
in their estimates from Il deg, to Ia
deg, by comparison with stars known
to me, and one, by the aid of a little
imagination, could see it for length
of l6 deg. Taking my own estimate,
the tail had increased in length so per
cent. within these two days, although
part of this may be due to unnoticed
haze in the atmosphere on the Sd. a
The brightness of the comet on the
Sd and 9Th indicates that it will have
an equality on July l4th with the star
Altar, the brightest star, with three
exceptions, visible in the evening with
it. AS Donati's comet equalled Arc
turns in brightness, am by no means
confident that the present will be
equally bright.
The motion of the earth is ], $780, 0,000
miles per day and that of the comet
about 1000, 600 miles per day, and will
continue about the same so long as ii
remains visible. The motion of that
part of the tail nearest us is nearly 6,
100000 miles per day that is, 20 miles
per second, which is 5000 times faster
than the motion of an express train.
The thickness of the tail l assume at
about 5,000,O0O miles at the distance
of 26,DO0,000 miles from the head,
when it shall have reached that length.
If the earth were to pass centrally
through it the passage would occupy
about twenty-four hours. Passing
through the extreme edge, as ] at first
thought possible, would not occupy
more than four to six hours. My
computations indicate that the near
est approach TO the center of the tail
will be not less than 100000 miles,
which would be distance from the
edge of the tail of 100000 miles,
which is six times the distance to the
moon. But this will be sufficiently
near to cause it to appear enormously
large, if ii. can be seen at all, of which
| hope to be able TO speak more def
nitely within a few days. One thing
is certain, it will be there whether VIC
can see it ornot.
HENRY M. PARKHURsr.
New York, July 6, 1874.