Intelligence and Miscellaneous Articles, 407 



It has now been found that even at one and the same temperature, and 

 that a temperature (150° C.) which is very far from a red heat, dif- 

 ferent substances emit very different kinds of heat, and that thus, in 

 any space whatever, an extraordinarily large number of different wave- 

 lengths are continually crossing each other. This manifold crossing 

 is especially increased by the selective absorption which is met with 

 at different surfaces. 



Hence an eye which could discriminate the various wave-lengths 

 of heat like the colours of light, would see all objects in the most 

 different colours, even if they were not specially warmed. — Poggen- 

 dorff's Annalen, September 1869. 



°N THE LUMINOUS EFFECTS PRODUCED BY ELECTROSTATIC IN- 

 DUCTION IN RAREFIED GASES. LEYDEN JAR WITH GASEOUS 



COATINGS. NOTE BY M. F. P. LE ROUX. 



I. In a previous communication I described a certain number of 

 experiments which render evident the induction that takes place in 

 the body of rarefied gases, in vessels formed of a continuous insula- 

 ting material, and devoid of all metallic communication with the ex- 

 terior. These effects are manifested by true currents which illumi- 

 nate the gaseous masses in the body of which they are propagated. 



The facts here treated of have interesting consequences in the way 

 of explaining certain meteorological phenomena. They must play 

 an important part in the luminous manifestations of the electricity of 

 the globe to which is given the name of polar auroras ; and the dif- 

 fused part of the glows which constitute them, it seems to me, should 

 be attributed to an electrostatical induction seated in the higher 

 strata of the atmosphere, under the influence of the discharges of the 

 aurora. 



This same induction, operating in the rarefied strata of the atmo- 

 sphere, seems to me to furnish the explanation of a remarkable cir- 

 cumstance which often accompanies the lustre of the lightning-dis- 

 charge. When the lightning strikes, it produces an illumination 

 which surrounds the perfectly serene regions of the sky, when there 

 are any ; the circumstances of this phenomenon do not appear to 

 me to be capable of explanation by a phosphorescence of the atmo- 

 sphere properly so called. It seems to me that we must rather per- 

 ceive in it the manifestation of the return shock which must take 

 place in the higher regions of the atmosphere at the moment when, 

 through the effect of the discharge which constitutes the lightning, 

 the clouds revert to their neutral condition. 



As to the heat-lightning, so called, which is observed in a clear 

 sky at a certain height above the horizon, there is no doubt that 

 it is due to the same cause, 



II. The electrostatical induction of rarefied gaseous masses ap- 

 pears to operate instantaneously across insulating envelopes ; at 

 least this is what seems to me to result from the working of the 

 apparatus that I have constructed, in which the illumination is pro- 



