﻿250 Chevalier W. von Haidinger on the Luminous, Thermal, 



perfectly applicable to the process here in question. The cele- 

 brated Professor G.V. Schiaparelli announces it in these terms: 

 "While the meteoric substance is dispersed through the atmo- 

 sphere, this vis viva, being transformed into heat and light, is 

 entirely destroyed." This explanation is rejected by Professor 

 Daubree, who says (p. 8), "The recent investigations as to the 

 mechanical production of heat have induced some to suppose the 

 heat of meteorites to be the consequence of their loss of vis viva. 

 This supposition is in contradiction to the carbonaceous meteo- 

 rites, which, instead of being hot as far as their centre, as they 

 ought to be according to this supposition, include substances 

 liable to be altered or dispersed by a slight increase of tempera- 

 ture." He has not, however, considered this transformation as 

 proceeding not suddenly, but by degrees, in proportion to the at- 

 mospheric resistance, and only on the surface where the air is 

 in contact with the meteoric nucleus. He supposes likewise the 

 meteorites to come cold out of cosmical space on account of their 

 composition being easily destructible by heat, although he does 

 not mention the extremely low temperature which must be sup- 

 posed to exist in cosmical space. The learned Professor, when 

 ascribing (p. 9) the thermal phenomena observed in meteorites 

 to the development of electricity provoked by violent friction, is 

 rather commenting on than contradicting von Haidinger' s views. 

 It may be a question what idea is to be conceived of the 

 dispersion of a swarm of meteors, different in size, without de- 

 tonation and at the moment of quietly entering the atmosphere. 

 Director Julius Schmidt has witnessed this phenomenon at 

 Athens, October 18, 1863, and sketched it in the diagram, fig. 3 

 (reproduced from memory ; part of the luminous tail spreading 



Fig. 3. 



West 



Athens, Oct. 18, 1863, 14 h. 55 m. Course of the meteor E. to W. 



eastward behind the meteor is left out for want of space) . The 

 atmospheric resistance acts more powerfully on bodies of compa- 

 ratively greater surface, while the larger and heavier ones move 

 forward. The most minute particles remain behind in form of 

 a tail. The telescope has dissolved into a group what seemed to 

 be a single meteor ; it is as possible that bodies nearly approach- 

 ing each other, and even wrapped up in the same meteoric enve- 

 lope, may proceed in common. The ideal sketch, fig. 4, may 



