74 Royal Society : — 



discovered about six years ago, but the true nature of which he failed 

 to recognize. To complete the series, it remains only to examine 

 the third volatile base and the oxide of tetrethylene-diammonium. 



The observations which I have the honour of submitting to the 

 Royal Society coincide in every point with the first note upon this 

 subject which I presented nearly two years ago. I have simply 

 carried out somewhat more in detail the sketch traced in my former 

 communication. 



In conclusion I may state a fact which has also been observed 

 by M. Cloez, viz. that the action of dibromide of ethylene upon 

 ammonia gives rise to the formation of bases not directly belonging 

 to the series which we have discussed. In searching for the method 

 of purifying the ethylene bases, I have been obliged to examine also 

 the terms of the other group ; but since these substances do not 

 necessarily belong to this part of the inquiry, I omit for the present 

 to enter more fully iuto their examination. 



" On the Forces that produce the great Currents of the Air and of 

 the Ocean." By Thomas Hopkins, Esq. 



In this paper the writer pointed out 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. 



Jan. 19. — Sir Benjamin C. Brodie, Bart., President, in the Chair. 



The following communication was read : — 

 " On the Interruption of the Voltaic Discharge in Vacuo by Mag- 

 netic Force. ,, By J. P. Gassiot, Esq., F.R.S. 



The late Professor Daniell, in his Fifth Letter on Voltaic Combina- 



