Omaha daily bee., 1899-11-19

they occupy several years in passing a giver
point. This accounts for the fact that W,
see sometimes more, sometimes fewer. o
these stars as the earth crosses their orbi
! every year on the 18th OF November. W.
are at that point only on that day and car
| only see the swarms on that day. But 1t |!
years in passing and so we may and do pas!
through successive portions OF 1t on the an
niversary OF the same day for years, that is
1 while the Jeonid swarm Is passing the
earths orbit. For the 'Leonids" unlike
| the Andromedes of November 2S, which
| rather overtake than cross us
move in a direction opposite to that OF the
earth. The hands of a clock dial at three
minutes after 6 will illustrate the relative
movements OF the earth and the Leonids on
November Is. The earth is moving along
the hour hand, the meteors along the minute
hand and both toward the center of the dial
and beyond in straight lines. The velocity
of the meteors is twenty six miles second;
we are moving at eighteen miles second
Hence we meet with head-on speed oi
forty-four miles a second, and the meteors
are ignited by friction with our atmosphere
emitting a swift. bright blush light. This
November 10 meeting of the earth and the
meteors is again like a grade crossing. where
two railroads intersect on the level. But
the meteor orbits or tracks are so many and
so wide that 1t takes the earth about three
perhaps even five, days to cross 1t, even
with its great velocity Of eighteen miles q
second. The attraction of the sun and
planets has so disintegrated the nucleus oil
the ancient parent comet that 1t is drawn
out into broad ribbon, so that the meteors
are not so densely packed and their display
is less luminous Hence, as the earth is at
the appointed grade crossing only on NO
vember Is, only thus will they be visible in
their briliancy. On November Ia and there
after until November 13 of the next
year countless millions will pass that spot,
but the earth is not there. AS the ribbon
is so long that it takes three years to pass
in review the advance guard Of this army
of stars was visible last year, while the
rear guard will be observed as we are cross
ing the Leonid orbit next year on Novem-
ber 10.
Mode of Observation.
The method ordinarily followed by as
tronomers in observing shooting stars is not
a particularly difficult one. The time, first
of all, Of the appearance of the star is care
fully noted. Next the path of the meteor
as seen in the heavens is drawn upon the
star chart This line is continued backward
and the intersections Of all paths similarly
drawn is thus found. This determines the
radiant from which they all emanate and
establishes the orbit of the meteors. TO
ascertain the number of stars that fall, the
number that falls every five minutes is
counted. This number will determine the
time Of maximum fall. This counting is
done usually with the naked eye and is
feat easily accomplished. even by an ANA
teur Another method employed by as
tronomers in determining the elements Of
shooting stars is the use Of an ordinary
stationary Photographic camera set every
half hour, or better still, the use of several
cameras strapped to an equatorial and moved
by clock work. This method saves the
labor of drawing the paths upon the star
chart and enables the observer to count the
stars afterwards at his leisure. But 1t
does not indicate the time Of the appearance
of the shooting stars. This Photographic
method is not, however, used in more than
three or four observatories in this country.
The apparatus is too expensive.
WILLIAM +. RIGGE, S. j.,
Creighton College Observatory.