434 Mr. R. P. Greg on the Lunar Origin of Aerolites. 



tions, whether a mass iirojocted from a volcano in the moon 

 weighed 30 lbs. or 30,000 lbs. ; but such a difference Dr. Smith 

 seems entirely to have overlooked ; it is sufficiently great, how- 

 ever, in the ])resent state of our knowledge of this subject, to 

 over-rule the possibility that the larger iron meteoric masses can 

 have a lunar orix/in. 



Dr. Smith gives us the result of some interesting experiments, 

 to prove the fallacy of judging of the actual size of meteors by 

 their apparent size; I shall again quote his own words : — 



" In my experiments, three solid bodies in a state of vigorous 

 incandescence were used : 1st, charcoal points transmitting elec- 

 tricity ; 2ndly, lime heated by the oxy-hydrogen blow-pipe ; 

 3rdly, steel in a state of incandescence in a stream of oxygen 

 gas. They were observed on a clear night at different distances, 

 and the body of light (without the bordering rays) compared 

 with the disk of the moon, then nearly full, and 45° above the 

 horizon. Without going into details of the experiment the re- 

 sults will be tabulated. 



Actual diam. Apparent diam. Apparent diam. Apparent diain. 



as seen at 10 in. at 200 yards. at i mile. at 4 mile. 



Carbon points ~-^ of *" inch, J. the diam. moon's disc, 3 diam. do. 3vy diam. do. 



Lime H"-ht . . -*- ... ^ ... 2 ... 3" ... 



In candes. steel y% ••• \ ••• 1 ••• 1 



" If then the apparent diameter of a luminous meteor at a 

 given distance is to be accepted as a guide for calculating the 

 real size of these bodies, the 



Charcoal points would be 80 feet in diam. instead of f|j of an in. 

 Lime ... ... 50 ... yjj 



The steel globule ... 25 ... to ••• 



"I need not here enter into any explanation of these de- 

 ceptive appearances, for they ai"e well -known facts, and were tried 

 in the present form only to give precision to the criticism on the 

 supposed size of these bodies." 



Dr. Smith is evidently anxious to reduce to a minimum the 

 size of the lunar aerolites, and proceeds a little further on to 

 say:— 



" This then will conclude what I have to say in contradiction 

 to the supposition of large solid cosmical bodies passing through 

 the atmosphere, and dropping small portions of their mass. The 

 contradiction is seen to be based ; first, upon the fact that no 

 meteorite is known of any very great size, none larger than the 

 granite balls to be found at the Dardanelles along side of the 

 pieces of ordnance from which they are discharged ; secondly, on 

 the fallacy of estimating the actual size of these bodies from 

 their apparent size ; and lastly from its being opposed to all the 



