470 Intelligence and Miscellaneous Articles. 



A series of observations made on the 1st of April on Mont Solere, 

 at a height of about 1 250 metres, gave me the following values of 



the ratio — : — 



Time. 



t 

 T 



Time. 



t 

 T' 



h m 

 2 4 

 2 16 

 2 31 



0-577 

 0-578 

 0597 



h m 

 5 26 

 5 38 

 5 50 



0-586 

 0531 

 0-528 



The value of — , especially when the sun is near the horizon, ap- 

 peared greater at Geneva ; but it would be premature to deduce from 

 the observation of a single day a general conclusion on the influence 

 of latitude. 



Substituting for the water in the tube a solution of alum, I ap- 

 tained (at Geneva, the 21st of March) the following results, which 

 approximate closely to those given above :• — 



Time. 



t 

 T* 



Time. 



t 

 T' 



h m 

 7 18 

 7 30 

 7 42 



0-397 

 0-462 

 0-486 



h m 



9 16 



12 28 



5 30 



0-557 

 0-588 

 0458 



It follows from these observations that, in the conditions under 

 which I worked, the atmosphere stops the luminous rays in greater 

 proportion than the obscure rays which are absorbed by water. 

 There is an obvious analogy between this result and the well-known 

 property of the atmosphere, of allowing the red rays to pass more 

 easily than the more refrangible rays. 



It will be observed that the above experiments were made in cold 

 and dry weather. It will be interesting to ascertain whether the 

 same result holds when the tension of vapour is more considerable. 

 — Comptes Rendus, April 20, 1868. 



ON THE INTERNAL WORK OF GASES. BY M. A. CAZIN. 



I have made observations on the variations of pressure in a 

 gaseous mass which has suddenly passed from one reservoir into 

 another, from the moment at which the pressure began to be equal 

 to the time that the gas had assumed its original temperature. 



