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 atmosphere. 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 certain comets. 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 



