37 



no regular interval between the shocks, which sometimes followed so 

 quickly as not to be counted, while other animals could scarcely be 

 provoked to give any shock. 



The electric discharge was mostly accompanied by an evident mus- 

 cular action in the animal, with an apparent swelling of the superior 

 surface of the organs, and by a retraction of the eyes. 



Two of these fish being placed in different buckets of water, one, 

 which was irritated so as to give frequently repeated shocks, soon 

 became languid, its shocks diminishing rapidly in intensity, and it 

 soon died ; but the other, not being irritated, continued living to the 

 third day. And this was universally observable, that those which 

 parted with shocks most freely soonest died. 



A Torpedo, in which the nerves proceeding to the electric organs 

 had been divided, seemed to have no power of giving shocks, but ap- 

 peared just as lively as another Torpedo taken at the same time, and 

 placed in a separate bucket of water uninjured. 



Of two Torpedos taken at the same time, one had the electric or- 

 gans divided. They were then both irritated equally, so that the 

 perfect animal was soon exhausted of all power, and died ; but the 

 other, which had lost the power of giving shocks, appeared as viva- 

 cious as before, and lived to the second day. 



An animal, from which one electric organ had been removed, was 

 found still capable of giving shocks, though possibly not so strong as 

 before. 



Another fish, in which only one nerve to each organ had been di- 

 vided, was also able to give shocks as before. 



When they were held only by the tail or by the extremity of their 

 lateral fins, they appeared to have no power of giving shocks. 



Mr. Todd infers from these experiments, 



That the electric discharge is a vital action. 



That it is perfectly voluntary. 



That frequent action is injurious to life, and may soon exhaust it. 



That an animal deprived of this power is more vivacious, and lives 

 longer than one which exerts this means of exhausting itself. 



That both organs are not necessary for giving the shock. 



That all the nerves of one organ are not necessary to be entire. 



That a most intimate relation subsists between the nervous system 

 and the electric organs. 



Direct and expeditious Methods of calculating the Excentric from the 

 Mean Anomaly of a Planet. By the Rev. Abram Robertson, D. D. 

 F.R.S. Savilian Professor of Astronomy in the University of Ox- 

 ford, and Radcliffian Observer. Communicated by the Right Hon. 

 Sir Joseph Banks, Bart. G.C.B. P.R.S. Read February 15, 1816. 

 \Phil. Trans. 1816,^. 127.] 



Each of these methods, says the author, is to be considered as 

 direct, although it proceeds through the medium of Cassini's ap- 

 proximation, which, as here used, can only be regarded as a first step 



