310 Torpedo Experiments, July, 1775 



I then elect, i row of battery till pith el. sep. to same degree, and commun. its 

 elect, to rest of battery and received the shock of 5 rows of it in same manner. 

 The shock seemed to be nearly of same strength, perhaps rather less. 



Therefore shock of 5 rows elect, to a given degree seems about equal or 

 perhaps rather less than that of i row el. to 3 times that degree. 



614] The mean thickness of the section of the elect, organ in the section 

 given in Mr H.* paper, in which the breadth is 10-3 inches, that is, the same as 



I2 l 

 my torpedo's, is 1-3 inc.; the area of one organ is 2-5 x 5j x = gj sq. inc., 



as found by cutting out a piece of paper of that size and weighing it. 



And according to Mr H. there are about 150 partitions in i inch, therefore 

 comp. charge both organs reckoned in old way is 



19 x 1-3 x 150 x ^ x 150 = 748,000, 



and the real charge is 1122,000 inches of el. supposing the partitions to consist 

 of plates of white glass ^^ inc. thick, which is about 2\ times as much as my 

 battery, that being = 451,000 inc. el. 



615] Tried with the 2 nd leather torpedo, new covered, in large trough full 

 of water, the torpedo laid flat as in figure, 

 the electrical organ being (as supposed) 3 

 inches under water. 



If torpedo was tried out of water with 

 i row to i\ comm. to 7 and touched with 

 hands in usual manner, the shock was just 

 felt in hands, and if touched with metals, 

 was just sensible in elbow. 



Tried under water in above-mentioned manner with 7 rows el. to 4, the 

 upper surface being touched with the pestle of a mortar held in one hand, the 

 other hand dipt into water as far as wrist, a shock in the wrist of the hand in 

 the water I believe full as strong as the former. 



The place where the hand was dipt into water was about n inc. from the 

 front of the fish, and conseq. about 14 from elect, organ. 



Tried in the same manner as before, except that the fish lay in an open 

 wicker basketf, just big enough to receive it, and which had been soaked for 

 some days in salt water. The shock seemed much the same. 



Holding hand in water in same manner as before without touching torpedo 

 no sensation. 



With three rows to ij out of water, the shock was stronger if I touched 

 convex side with one hand laid flat on elect, organs than if I touched flat side 

 in same manner, but the difference was not great. 



Charge of 7 rows el. to 4 is to that of i row el. to ij as 19-6 to i. 



The water appeared by its spe. gra. to contain .^ of salt. 



* ["Anatomical observations on the torpedo." By John Hunter, F.R.S., [Phil. 

 Trans. 1773]. Art. 436.] t [Art. 421.] 



