PHILOSOPHICAL SOCIETY OP WASHINGTON. 189 



Mr. J. W. Powell made a communication on 



THE LANDS OF THE ARID REGION OP THE UNITED STATES, 



and expressed the belief tliat of the whole area of Utah, 2^^^ per 

 cent, was arable, and 23 per cent, was of use for the growth of 

 timber ; and of the last, almost half was covered with standing 

 timber more or less scattered, and the remaining portion had been 

 devastated by fires or otherwise. 



The subject was discussed by Messrs. Gilbert, White, Coues, 

 and Ward. 



Mr. W. B. Taylor supplemented his remarks of the last meet- 

 ing by a further discussion of the analogy of the Rrngs of Saturn, 

 as to the probable differences of the outer and inner elements, 

 with the satellites of Mars. 



Mr. Hall stated that he had consulted the memoirs of Her- 

 fichel on the Rings of Saturn, and according to that astronomer's 

 observations there was no appreciable difference in the periods 

 of rotation of the outer and inner portions. 



140th Meeting. March 30, 1878. 



Vice-President Taylor in the Chair. 



Fifty-six members and visitors present. 



The death of Mr. Ferdinand Kamppp, a member of the Society, 

 was announced. 



Mr. Elisha Foote read a paper on 



THE causes op electrical DEVELOPMENTS IN THUNDER STORMS, 



in which he attributed the electrical phenomena to the condensa- 

 tion of vapor, and in support of his views, detailed experiments 

 which he had made. 



