356 M. Haidinger on the Phenomena attending 



In his paper on the constitution of the electric spectra of certain 

 gases and vapours (see PoggendorfFs Annalen, 1859, vol. cvii. 

 p. 505), the illustrious Professor says, " What is the thing 

 emitting light when an electrical discharge takes place through 

 the narrow passage of a Geisslerian tube, as much exhausted of 

 air as possible, and including gas or vapour ? There is no light 

 unless some ponderable substratum emits it; there is conse- 

 quently no electrical light in the abstract sense of the word. All 

 my observations have confirmed me in this persuasion. But 

 how is electricity acting here on the gaseous particles ? In my 

 opinion only as an exciter of heat. The gaseous particles become 

 incandescent. The thick glass in the narrower portion of the 

 Geisslerian tube is very notably heated when the discharge from 

 RuhmkorfPs apparatus passes through the gas contained in it. 

 If, then, the heat transmitted to the glass from the dispersed 

 gaseous particles, whose tension is often measurable by fractions 

 of millimetres, increases to a notable degree, to what a degree 

 of intensity must these particles be heated [" 



The cosmical orbit of the meteorite M entering the terrestrial 

 atmosphere A v . 



(fig. 2) termi- 

 nates at C ; from 

 this moment the 

 meteorite be- 

 longs to our earth, 

 and falls straight 

 down from C 

 (where, after ex- 

 ploding, its light 

 is extinguished) to D on the earth's surface. The line C D repre- 

 sents its terrestrial orbit. 



Terrestrial attraction is quite an insignificant element com- 

 pared to the planetary or cosmical impulsion peculiar to any 

 meteorite ; and but for the resistance offered by the atmosphere, 

 few or no meteorites would reach the surface of our earth, except 

 those whose orbits were directly aimed towards it. 



Meteoric stones after falling appear black ; and their ena- 

 melled crust proves them to have undergone superficial fusion 

 from exposure to high temperature. Their interior is frequently 

 not more heated than would permit of their being held in the 

 hand without inconvenience. 



This is no matter for surprise, as the stone having quite re- 

 cently come from the cold regions of interplanetary space, a 

 compensation may be supposed to take place between the out- 

 side and the inside. 



Fragments of the Dhurmsala meteorite (Punjab, 14th July, 



