194 
HAROLD’S DISCUSSIONS. 
reach the earth. When the larger 
earth they sometimes penetrate the 
Fig. 97.—The Great Comet of 1882, 
October 19th (Artus). 
ones come to the 
soil for some dis¬ 
tance, produ¬ 
cing a quaking 
in the neighbor¬ 
hood. 
A class of 
celestial visitors 
which usually 
receive much at¬ 
tention is the 
comets. They 
consist of a nu¬ 
cleus with a 
streamer of more 
or less length, 
usually spoken 
of as the tail. 
This nucleus is 
probably solid, 
but the tail con¬ 
sists evidently of 
gaseous mate¬ 
rial, as stars 
have been seen 
through it. 
Some comets 
move in regu¬ 
lar elliptical or¬ 
bits, but very 
eccentric ones. 
