NATURAL PHILOSOPHY. 125 



It has been frequently surmised, and the anticipation is, I believe, a 

 strictly philosophical one, that a power which, so far as we have the 

 means of judging, prevails everywhere in our own planet, should also 

 prevail in other bodies of our system, and might become sensible to 

 us, in the case of the sun and moon particularly, by small perturbing 

 influences measurable by our instruments, and indicating their respec- 

 tive sources by their periods and their epochs. As yet we know of 

 neither argument nor fact to invalidate this anticipation ; but, on the 

 contrary, much to invest it with a high degree of probability. 



ON THE MOTION OF FLUIDS FROM THE POSITIVE TO THE 

 NEGATIVE POLE, OF THE CLOSED GALVANIC CIRCUIT. 



WIEDEMANN has communicated to the Prussian Academy of 

 Sciences, a memoir on the mechanical action of the voltaic circuit 

 which is of essential interest and importance. The apparatus employed 

 consisted of a porous earthenware cell, closed at the bottom and 

 terminated above by a glass bell firmly cemented to the upper edge 

 of the cylinder. Into the tubulure of the bell a vertical glass tube was 

 fitted, from which a horizontal tube proceeded so as to permit the 

 fluid raised to flow over into an appropriately placed vessel. A wire 

 serving as the negative pole of a battery passed down through the 

 glass bell into the interior of the porous cylinder, where it termi- 

 nated in a plate of platinum or copper. Outside the porous cylinder 

 another plate of platinum was placed and connected with the positive 

 pole of the battery. The whole stood in a large glass vessel, which, as 

 well as the interior porous cylinder, was filled with water. The inten- 

 sity of the current was measured by a galvanometer. As soon as the 

 circuit was closed, the liquid rose in the porous cylinder and flowed 

 out from the horizontal tube into a weighed vessel. The results 

 obtained by means of this apparatus were as follows : 



1. The quantity of fluid which flows out in equal times is directly 

 proportional to the intensity of the current. 



2. Under otherwise equal conditions, the quantities of fluid flowing 

 out are independent of the magnitude of the conducting porous 

 surface. 



To avoid any uncertainty arising from the laws of the flow of liquids 

 through small orifices, Wiedemann measured the intensity of the 

 mechanical action of the current by determining the height of a 



tt 



column of mercury which would hold the transferring force in equili- 

 brium. For this purpose a graduated tube or manometer filled with 

 mercury was attached to the extremity of the horizontal tube above 

 mentioned : with different currents and porous surfaces of different 

 extent, the mercury in the manometer rose to different heights. By 

 the measurements of these heights the following results were ob- 

 tained : 



3. The height to which a galvanic current causes a fluid to rise, is 

 directly proportional to the intensity of the current and inversely pro- 

 portional to the extent of the free porous surface. 



