654 Intelligence and Miscellaneous Articles, 



such instruments is merely the relative state of activity of the whole 

 or of a portion of the charge, in a given direction, taken in terms of 

 a given statical force, either attractive or repulsive, and by the instru- 

 mentality of which we may occasionally infer the quantity oi electricity 

 in operation at the instant of discharge. I further show, by reference 

 to investigations prior to those of Dr. Riess, that the diminished 

 effect of the electrical discharge observed in accumulating and dis- 

 charging a given quantity of electricity from an increased surface, 

 taken in parts, as in the case of extending a battery by the addition 

 of other jars, arises solely from the resistance we thereby introduce 

 into the circuit of discharge, and not from any change of tension in 

 the accumulated electricity itself; and in confirmation of this, I call 

 Dr. Riess's attention to the fact, as a crucial experiment, that when 

 the given quantity of electricity is accumulated on an undivided sur- 

 face, that is to say, when it is collected on the extended surface of a 

 single large jar, for example, instead of an extension of surface by 

 means of several lesser jars, the surfaces being in each case alike 

 extended, — or when collected on two separate jars of such unequal 

 surfaces and magnitudes as to give electrometer indications of ex- 

 tremely different intensities, — then no change takes place in the 

 heating effect of the discharge ; consequently the mere extension of 

 the surface of the battery, taken alone, has really no influence on 

 the result ; and Dr. Riess's law of electrical heat falls to the ground. 

 Now to this experiment Dr. Riess makes no reply. 



It would be easy for me to animadvert effectively upon all Dr. 

 Riess has advanced in his last communication. I am not certainly 

 open to the censure of having taken Haldane's method of measuring 

 quantity as my own ; and in confirmation of this I beg to refer to my 

 paper in the Transactions of the Plymouth Institution, also to page 

 358, Phil. Mag. vol. xi., referred to by Dr. Riess himself, I cer- 

 tainly resorted to the method at first, without being aware that the 

 same method had been already employed by Haldane ; but I was 

 very cautious in claiming any precedence, or stating, as Dr. Riess 

 has done (Pogg. Ann. vol. xl. p. 324), that I was the " first to apply 

 this method" practically, although I certainly employed it many 

 years previously to the appearance of Dr. Riess's paper in Poggen- 

 dorff, and precisely in the way described by him, that is to say with 

 a Lane's bottle in communication with the external coating, instead 

 of a Cuthbertson's balance as used by Haldane. . 



I have the honour to remain, Gentlemen, 



Your very obliged and obedient Servant, 



6 Windsor Villas, Plymouth, W. Snow Harris. 



Dec. 20, 1856. 



