235 



II. " On the Forces that produce the great Currents of the Air 



and of the Ocean." By THOMAS HOPKINS, Esq. Commu- 

 nicated by J. P. JOULE, LL.D. Received December 2, 



1859. 



(Abstract.) 



In this paper the writer pointed oat the fact that we have at 

 present no satisfactory evidence in books of what are the immediate 

 causes of the great currents of the air and of the ocean ; and he 

 maintained that the liberated heat of condensing vapour is the cause 

 of these currents. He then proceeded to show that all the great 

 winds terminate in comparative vacua created in particular localities 

 where much vapour has been condensed ; and contended that such 

 vacua enable and cause heavier air to press and flow towards the 

 parts which have been rendered light, to re-establish the equilibrium 

 of atmospheric pressure, thus making heat the disturbing power 

 in the aerial ocean, and leaving gravitation to act to restore an 

 equilibrium. The great primary currents of the ocean were also 

 described, and they were shown to be so situated as to be under the 

 influence of the principal winds, which, in their passage over the 

 waters, press on them, and force them forward as currents. These 

 currents were maintained to be of a velocity, extent, and depth 

 proportioned to the strength and continuity of the wind, showing 

 that the pressure of the air on the water, whilst moving over it, is 

 capable of producing the movement which takes place. When, how- 

 ever, water is put into motion, it may be obstructed by land, and 

 turned from its direct course, and in that way be made to form 

 secondary currents. But it was contended that heat of vapour, set 

 free in the atmosphere, is the force which disturbs the equilibrium 

 of pressure, and either directly or indirectly produces all the great 

 continuous movements that take place both in the atmosphere and 

 the ocean. 



III. " On the Movements of Liquid Metals and Electrolytes in 

 the Voltaic Circuit." By GEORGE GORE, Esq. Commu- 

 nicated by Professor TYNDALL. Received December 1, 

 1859. 



1 . It has long been known that when a globule or layer of pure 

 VOL. x. s 



