110 BLECTEIO FORCE CHAP. X. §. I. 



opinion the doubts expressed by these inquirers. 

 But the positive evidence adduced by Du Bois 

 Kbymond by means of his delicate galvanometer, 

 combined with that of Matteucci obtained by means 

 of the frog, only made it incumbent upon the 

 opponents of Du Bois Keymond to disprove his 

 conclusions, if capable of disproof, more by stronger 

 experimental evidence than by theoretical arguments; 

 hence the renewal of the present inqiiiry. 



In relating the experiments, to avoid unnecessary 

 prolixity, I shall endeavour to be as concise as pos- 

 sible, although it may be considered that the various 

 sources of error have not been sufficiently eliminated. 

 My great point, however, will be to establish facts ; 

 and whatever observations it may be necessary to 

 make in reference to the origin of the effect pro- 

 duced, these will form the subject of the concluding 

 remarks, and I shall just relate in a general 

 manner some results that were first obtained by 

 means of a galvanometer consisting of but few coils. 

 To two brass handles of an ordinary medical electro- 

 magnetic machine, were attached thick copper wires, 

 each about 8 inches in length, and bent. Similar 

 copper wires were connected with the galvanometer, 

 their free ends communicating with mercurial cups, 

 these cups forming the means of connexion with the 

 brass handles. Holding the metallic handles firmly, 

 grasping one of them and conti-acting the muscles 

 of the arm powerfully, and doing this alternately 

 with each arm, 1 at first failed to obtain any, or if 



