S58 Dr. Faraday's Experimental Researches in Electricity^ xv. 



lions, that " if any hexagon be circumscribed about any conic 

 section, and the opposite angles be joined, the three diagonals 

 have a common intersection." I believe mine was the first at- 

 tempt to prove this very curious proposition algebraically, but 

 a simpler demonstration of that theorem has since been given 

 by an anonymous writer in the Cambridge Mathematical Jour- 

 nal, and it follows from the method there adopted that the 

 property which I had noticed for the parabola, 



3/l-^2+i/3-y4+J/5-J/6 = 



may be extended to any polygon of an even number of sides 

 circumscribing a parabola, so that 



J/l— V9+y»-3/4 +3/2n-. -3/2« = 0. 



LIV. Experimental Researches iti Electricity. — Fifteenth 

 Series. By Michael Fauaday, Esq., D.C.L., F.R.S.f 

 Fullerian Prof. Chem. Roijal Listitution, Corr. Memb. Royal 

 and Imp. Acad, of Sciences, Paris, Petersburgh, Florence, 

 Copenhagen, Berlin, Gottingen, Modena, Stockholm, S^c. SfC* 



§ 23. Notice of the character and direction of the electric force 



of the Gymnotus. 

 1749. TirONDERFUL as are the laws and phaenomena 

 ^ ' of electricity when made evident to us in inor- 

 ganic or dead matter, their interest can bear scarcely any com- 

 parison with that which attaches to the same force when con- 

 nected with the nervous system and with life ; and though 

 the obscurity which for the present surrounds the subject 

 may for the time also veil its importance, every advance in 

 our knowledge of this mighty power in relation to inert things, 

 helps to dissipate that obscurity, and to set forth more pro- 

 minently the surpassing interest of this very high branch of 

 Physical philosophy. We are indeed but upon the threshold 

 of what we may, without presumption, believe man is per- 

 mitted to know of this matter ; and the many eminent philoso- 

 phers who have assisted in making this subject known, have, 

 as is very evident in their writings, felt up to the latest mo- 

 ment that such is the case. 



1750. The existence of animals able to give the same con- 

 cussion to the living system as the electrical machine, the vol- 

 taic battery, and the thunder storm, being with their habits 

 made known to us by Richer, S'Gravesende, Firmin, Walsh, 

 Humboldt, &c. &c., it became of growing importance to 

 identify the living power which they possess, with that which 

 man can call into action from inert matter, and by him named 

 electricity (265, 351.). With the Torpedo this has been done 

 to perfection, and the direction of the current of force deter- 

 ♦ From the Philosophical Transactions for 1839, Part I. p. 1. 



