Solution of a Problem in Fluxions. 67 



The application of heat causes evaporation ; and the abstraction 

 of heat is followed by the deposition of vapor. Now during autumn, 

 the earth is becoming cooler in consequence of the loss of more cal- 

 oric than it receives. This change in the earth will produce a simi- 

 lar change in the atmosphere. The earth therefore by its contact with 

 a warmer stratum of air, will reduce its temperature, and the conse- 

 quence will be the deposition of vapor. This first stratum of air 

 will have the same effect upon a second ; and this again upon a third ; 

 and so on ascending. It is obvious then that there must be a contin- 

 ual deposition of vapor while the earth is cooling ; and this will be 

 greater in proportion as the process, which causes it, goes on more 

 rapidly. 



In the spring season the changes just described will take place in 

 a reversed order. The earth is becoming warmer; and the vapor 

 which arises from it, held in perfect solution by caloric, comes in 

 contact with the air, which is now colder than the earth ; and thus 

 has a portion of its heat abstracted, and consequently is deposited. 

 The refracting power of vapor however is nearly equal to that of 

 water; and consequently very much greater than that of air. Per- 

 haps the high refracting power, in the atmosphere, during the autumn 

 and spring season may be explained in this manner. 



I send you these suggestions respecting the Indian Summer, your 

 request in relation to which has been recalled to my mind by the ex- 

 istence of the peculiarity in the season here at present. They may 

 slightly interest you, if you have not yet received a satisfactory com- 

 munication on the subject. Z. 

 Baltimore, Dec. 15, 1830. 



Art. XII. — Solution of a Problem in Fluxions ; by Prof. Theo- 

 dore Strong. 



TO PROFESSOR SILLIMAN. 



New Brunswick, Feb. 12, 1830. 



Dear Sir — I send you the following method of extending (B) 

 (given at page 333 of the last Journal,) to the motion of a system 

 of bodies. Yours respectfully, T. Strong. 



I HAVE heretofore (virtually) supposed the mass of the moving 

 particle to be unity ; I will now suppose it to be m, or that it contains 

 the unit of particles m times ; the magnitude of m being supposed so 



