Variation of Temperature^ Sfc, in the Atmosphere, 175 



7th. By the help of the formula here given, the time sound 

 takes to travel over any given space, oblique as well as hori- 

 zontal, a problem, I believe, that has never been attempted, 

 may easily be determined. For instance, if a be the altitude 

 of the generation of sound, b that of the auditor, and q the 

 distance between the two, the time in seconds is 



and the time of travelling vertically from the top to bottom of 



the atmosphere, or the contrary, -^ — S, in which S is the hori*^ 



9 

 zontal velocity at the surface. If, therefore, S = 1089.4, as 



we have computed it at 32° Fahr., this time is 4' 47''. 4. 



I might here observe, by way of conclusion, that should any 

 one feel disposed to compute a table from our barometric the- 

 orem for the more easy measuring of heights, it would be 

 advisable td do it for 52° Fahr. The altitude being taken for 

 this temperature, and multiplied by twice the number of 

 degrees which the temperature of the lower barometer may 

 be above or beneath 52°, -nnnrth of the product will be the 

 only correction required, and is to be added or subtracted to 

 the preceding altitude, just as the lower barometer's tem- 

 perature happens to exceed or fall short of 52° Fahr. 



For the Cent, thermometer, the table had better be com- 

 puted for temp, or the freezing point. 



Proceedings of the Royal Institution, 



January 227id. 



Mr. Faraday on the Chevalier Aldini's proposed method of pre- 

 serving men exposed to flame. — We gave an account in our last 

 volume* of the plan which Aldini has proposed, and put into 

 practice, for the purpose of obtaining the above object. Since then 

 the Chevalier has arrived in town with his fire-proof clothings, the 

 power of which it was the object of Mr. Faraday to illustrate to the 



* Quarterly Journal, N. S. vol. vi. p. 398. 



