High-pressure Electric Accumulator. 203 



plate A than to the plate B (for the surface must be sym- 

 metrical on opposite sides of this line). It is also evident, on 

 account of this symmetry, that if, keeping B fixed, we could 

 transfer the plate A to the position A! at an equal distance at 

 the other side of the point F, the surface of equilibrium GW 

 would be the same, and that there would again be no ten- 

 dency to horizontal motion ; for, K / E / being eaual to K E, 

 the hydrostatic tension on the plate A! would courter balance 

 the diminution of the horizontal component of the surface- 

 tension. If the plate A! were now pushed nearer to B, the 

 horizontal component of the surface-tension between them 

 would remain the same, owing to the constancy of the contact- 

 angles, while the hydrostatic tension would increase as the 

 liquid rose between the plates and the curvature of its surface 

 increased. Consequently, at all distances less than that re- 

 ferred to there will be attraction. (The case is indeed the 

 same as that of fig. 3, with the difference that the lowest 

 element of the meniscus is inclined to the horizontal.) 



If, on the other hand, the plate A be withdrawn from the po- 

 sition A', the liquid between the plates will fall and the hydro- 

 static tension diminish, while the horizontal component of the 

 surface-tension will remain the same till the line of contact 

 with the plate A reaches the level of the free exterior surface, 

 when it must become the line of contrary flexure, to which 

 in all its positions we give the name F. Up to this position 

 the repulsion will accordingly increase; after this it will 

 diminish, since the inclination to the horizontal at F will 

 diminish as A recedes further. 



I am, Gentlemen, 



Your obedient servant, 



Clifton College, Bristol, A. M. WOKTHINGTON. 



Feb. 10, 1883. 



XXVII. A High-Pressure Electric Accumulator or Secondary 

 By Frederick John Smith *. 



THE modification of the gas-battery of Sir W. Grove 

 which the author has devised is as follows: — The gas- 

 battery of Sir W. Grove, as usually made, when used as an 

 accumulator, owing to the small quantity of gases that it 

 holds, soon runs down when in use. In order to make its life 

 longer, the author puts the gases under a high pressure; by 

 this means a large quantity of gas can be stored in a suitably 

 constructed instrument. The earliest form of battery, and 



* Communicated by the Author. 

 P2 



