152 



Mr. J. N. Lockyer. 



[Nov. 17, 



stone with a large iron would probably effect the driving of the stone 

 into fragments, while the iron would be liquefied so as to inclose some 

 of the fragments in its mass. 



These operations of Nature might go on either in free space, or in 

 the head of a comet, or in meteor-swarms. They probably cause the 

 appearance of the so-called new stars, and in these various circum- 

 stances the rate of subsequent cooling would of course be very different, 

 so that the results would be very different indeed. 



Large masses on collision probably destroy each other, produce 

 fragments and vapour, which again condense. The heterogeneous 

 structure is thus to a certain extent explained. On collision the part 

 of the substance of the meteorite given up will depend on the tempe- 

 rature, and thus a mass of metallic iron mixed with silicates at low 

 temperature will get rid of the iron at once, which must then perforce 

 condense in a separate swarm ; therefore under low temperature con- 

 ditions, say at aphelion, irons alone will be formed and the stones will 

 become spongy. The stones will absorb the carbon and hydrogen 

 vapours. 



General Conclusions. 



The general conclusions to which the foregoing investigations lead 

 may thus be stated : — 



I. All self-luminous bodies in the celestial spaces are composed of 

 meteorites, or masses of meteoritic vapour produced by heat brought 

 about by condensation of meteor-swarms due to gravity. 



II. The spectra of all such bodies depend upon the heat of the 

 meteorites, produced by collisions, and the average space between the 

 meteorites in the swarm, or in the case of consolidated swarms, upon 

 the time which has elapsed since complete vaporisation. 



III. The temperature of the vapours produced by collisions in 

 nebulas, stars without C and F but with other bright lines, and in 

 comets away from perihelion, is about that of the bunsen burner. 



IV. The temperature of the vapours produced by collision in 

 a. Orionis and similar stars is about that of the Bessemer flame. 



V. The line of increase of temperatures of the swarms of meteorites 

 and subsequent cooling of the mass of vapour produced, and the 

 accompanying phenomena, may be provisionally stated as follows : — 



