2^ Deilunktis etmcerning Eh^ric Tijh. 



fquare inches area at tlic bafe; then looo X 150 x 0,03 = 4500 fquarc niches. Now I 

 found that Mufcovy talc, of 0,01 inch thick, has twelve times the capacity of the glafs of a 

 jar of -21 fquare inches, which, from former experience, I know to be as thin as fuch jars 

 can be without danger of breaking by explofion ; and the torpedinal irenibrnne, being lefs 

 than one-third tlie thicknefs of the talc, will have three times the capacity ; thai is to fay, 

 its capacity will be tiiirty-(ix times that of ftout glafs--, or both organs will be equivalent to 

 45CC X 36 = 1620CO fquare inches, or 1125 fquare feet. 



My large jar, with Lane's ele£lrometer, meafuring a fpark about i-20Cth of an inch long, 

 gave very fenfible and rather unpleafant fliocks acrols the hand, and alfo the tremulous fen- 

 fation caufed as I fuppofe by the Impcrfefl: conducing power of the £kin with fo low an 

 intenfity. When the fpark was i-looth of an inch long, the fliock was flrong enough to 

 eonvulfe the hand, and at lefs than i-soth it was painfully ftrong. This laft was probably 

 ftronger than the fliock of the torpedo. If we therefore avail ourfelves of Mr. Cavendilh's 

 deduction, that, the quantity of eleftricity being increafcd in proportion as the length of 

 fpark is diminiflied, the fiiock will be rather greater than before, we may compute the length 

 of the fpark in the torpedinal {hock of the magnitude laft mentioned. For the organs of 

 the torpedo, compared as to their capacity with that of the jar, will be equivalent to 



1 :coo_ times as great, and they will give fuch afhock when charged as to afford a fpark 



■,\- of r - of an inch = —^ inch. No wonder, therefore, that the ftiock will not 



pafs through an interrupted circuit, and that the fpark is not exhibited. 



Refpeding the manner of operation, there are no faifls which Ihew how this charge is 

 aftually produced, maintained, and communicated. Whether ele£lricity be a£lually col- 

 lefted, compofed, or deeompofed in the organs of the fifli, or whether it finiply exifts in thofe 

 organs, as perhaps it may in all bodies, in the (late cf what is called compenfation, are quef- 

 tions concerning which we in fa6l know nothing. It has appeared to me, from the obfer- 

 vation of the high ele£tric ftate which talc naturally poffeffes, and from the innumerable 

 fhocks theelciTlrophore is capable of giving by mere change of arrangement, that a machine 

 might be conftrufted alfo capable of giving numberlefs fliocks at pleafure, and of retaining its 

 power for months, years, or to an extent of time of which the limits can be determined only 

 by experiment. I will not here defcribe the mechanical combinations which have occurred to 

 me in meditating on this fubjed, but fliall fimply fliew that the dimenfions of the organs of 

 the torpedo arc fuch as by certain very poffible motions, and the allowable fuppofition of con- 

 ^ufling and non-condu£ling powers, may produce the eflecls we obferve. How far it may- 

 be probable muft undoubtedly be left to future experimental refearch. 



In new talc, which had never been excited nor el;ftrified, and exhibited no figns of 

 eleftricity when applied to Bennet's eleclrometer, I found that the larainx were naturally 

 in ftrong, oppofite, eleflric ftates, counterb.ilancing each other. When they were torn 

 afundtr in the dark, they gave flaflies at leaft i-ioth of an inch long to each other. This is 

 1875 times the intenfity of the torpedinal ele£lricity, as before deduced. If, therefore, one 

 or more columns of talc, or other thin eledric plates l-300th of an inch thick, and making 

 up the furface cf the eledric organs of the torpedo, were fo conftrufted as that the plates 

 might touch each other by pairs only, naturally in oppofite ftates, and coated on the out- 



fide; 



