59 



IV. — On the Origin and Nature of the Forces that produce 

 Storms. By Mr. Alderman Hopkins. 



iRead December 16^ 1851.] 



Storms are strong winds, diiFering in degree and not in 

 nature, from ordinary winds or moderate breezes. All the 

 great movements of the atmosphere have their origin in 

 vertical currents which are produced by certain known 

 causes. These currents are fed from less or greater dis- 

 tances by horizontal currents, which press and flow towards 

 the area of ascent, and the horizontal currents, whether 

 they appear as moderate winds or storms, are thus pro- 

 duced by the ascending currents. These latter currents 

 are created by the aqueous vapour which is intermixed with 

 the gases of the atmosphere, heating these gases, through 

 the process of condensation, thus causing them to expand into 

 a larger space, and to press with less weight than they had 

 previously done on the surface of the earth. The adjoining 

 colder, and therefore heavier atmospheric gases then rush 

 under and force the warmer and lighter to ascend in the form 

 of vertical currents, and the heavier gases, being themselves 

 successively heated by the condensation of their vapour, also 

 rise, when more air presses towards the ascending mass, and 

 thus, these processes being repeated and continued, a Wind 

 or a Storm may be produced. 



But it has been said by persons who object to the hypo- 

 thesis here advanced, that the heat liberated in the atmosphere 

 by the condensation of aqueous vapour, is not sufficient to 



