METEORITE COLLECTION—HANDBOOK AND CATALOGUE, 29 
It may also be urged against this view that the volcanoes of the 
moon are not now active and the chances are exceedingly few that 
matter thrown from them in times past, once missing the earth, 
would ever reach it again. Also that from terrestrial volcanoes no 
substances like those forming the metallic meteorites have ever been 
ejected, and that, while in general the aerolites resemble volcanic rocks, 
they are in fact so distinct as to be readily distinguished from them. 
Another view which has been seriously urged is that meteorites 
have had a solar origin. 
Such a hypothesis, however, requires that solid bodies, some of 
them combustible, should come from the hot sun, and further that 
their paths should be in a line parallel to the ecliptic. The latter is 
not the case with the paths of many meteorites. 
By another hypothesis meteorites are regarded as having come 
from a shattered planet. It is evident from the facts just stated that 
such a planet could have had no atrnosphere. The supposition how- 
ever that it ever existed is purely an arbitrary one, as is also that of 
any internal force which could rend it in pieces. Moreover, from 
such a body we should expect fragments varying more in size than do 
those which have thus far come to us. 
We must therefore look to some other source for the answer to 
our question. The preponderance of opinion at the present day 
seems to be that it may be found in those strange, erratic bodies, the 
comets. 
We know that these are worlds without water, with a strange 
and variable envelope which takes the place of an atmosphere, worlds 
which travel repeatedly out into the cold of space and back to the 
sun and slowly go to pieces in the process. Such conditions corres- 
pond closely with those which we have already seen probably pre- 
vailed in the formation of meteorites. 
Still stronger evidence of the cometic origin of meteorites is to 
be found in the similarity between the orbits of groups of meteors 
and those of certaincomets. In 1866, Schiaparelli, having calculated 
the orbit and motion of the meteorites which produce the annual 
August star shower, found that they corresponded exactly with those 
of an observed comet. Later the orbit of Tempel’s comet was found 
to accord with that of the meteors of the November star shower and 
other parallelisms were noted for smaller showers. More remark- 
able still is the evidence afforded by the history of Biela’s comet. 
This comet, discovered in 1826 by Captain Biela, was found to have 
a period of revolution of 6.6 years and to regularly come into view 
