510 Sir W. Snow Harris on the Correct Interpretation 



more or less attractive of each other through the intermediate 

 glass. Hence the greater the extent of coating upon which a 

 given quantity of electricty is accumulated, the greater will be 

 the number of points of positive and negative force in absolute 

 contact with the intervening glass, and consequently the greater 

 the hold which the coatings may be supposed to have upon each 

 other; hence the greater will be the resistance to discharge 

 through an external circuit. On the other hand, supposing a 

 given quantity to be accumulated on a comparatively small ex- 

 tent of coated surface, then the fewer will be the number of 

 points of positive and negative force in immediate contact with 

 the intervening glass, and hence the coatings have a less hold 

 upon each other than in"the former case ; discharge in the direc- 

 tion of an external circuit will therefore be more free and more 

 readily effected. Now we know, from well-established experi- 

 ments, that the heat elicited in metallic wires by a given quantity 

 of electricity will be less as the resistance to discharge is greater; a 

 given quantity therefore discharged from a small extent of sur- 

 face may possibly have in some instances a somewhat greater 

 effect on a metallic wire than the same quantity discharged from 

 a large extent of surface, since the accumulated electricity dis- 

 engages itself more freely from a small surface than from a large 

 one ; the difference, however, is in no case considerable, and has 

 no relation whatever to what has been termed electrical intensity. 

 11. Again, as already observed (1), in the construction of voltaic 

 batteries, a few large plates principally relate to quantity ; whilst 

 in breaking up those plates into a long alternating series of 

 smaller plates, we are supposed thereby to impart to the elec- 

 trical agency intensity or tension. Here again we may perceive 

 that the apparently increased energy of the voltaic force in the 

 latter case is solely due to the increased quantity in a given point 

 of the terminating plates. Imagine, for example, four series of 

 voltaic plates of 1 foot square , to be divided and arranged in a 

 voltaic series of thirty-six consecutive plates of only 4 inches 

 square. In this case the terminating plates of the small series 

 have only the one-ninth part of the surface of the terminating 

 plates of the large series ; there would consequently (supposing 

 the quantity developed by the voltaic action to be the same in 

 each case) be nine times the quantity in a given point of the 

 terminating plates of the small series that there would be in a 

 given point of the terminating plates of the large series. 



Intensity therefore still agrees with quantity acting at a given 

 point, and by no means implies elastic power, tension, or any 

 other of those hypothetical occult qualities above alluded to. 

 The heating power of the current-discharge, however, from the 

 large plates, unlike that of the large and small jars above quoted, 



