ANTHEUA. 137 



pie of thermometers with me, one attached to a 

 mountain barometer, and tlie other detached ; 

 both of whicli, on being exposed to the vapour 

 composing the cloud, indicated the same degree 

 of temperature, namely 47**. Now, it is evident, 

 that this vapour could not possibly exist in a 

 state of concretion at a temperature elevated 16** 

 above the freezing point, and I may add, that it 

 did not exhibit any symptom of congelation 

 whatever; yet, when it had passed to a short 

 distance from us to the east, our shadows, with 

 their attendant anthelia and halos, were displayed 

 upon it with remarkable distinctness. The hour 

 at which these observations were made was about 

 6, p. M., and the sun was rapidly declining 

 towards the western horizon. It is deserving of 

 notice, that, more than an hour afterwards, the 

 temperature of the atmosphere, at the summit of 

 the mountain, was as high as 45°. 



From these facts we may safely conclude, that 

 congealed vapour is by no means an indispen- 

 sable requisite in the formation of anthelia and 

 halos ; all hypotheses, therefore, founded on this 

 supposition, must be abandoned or modified. 



Since the above was written, my friend, Mr. 

 Peter Barrow, has directed my attention to a brief 

 notice of a memoir by M. Ramond, on the 



