concerned in the Phenomena of ordinary Electricity, h$c. 341 



without considerable loss from dispersion ; or that dispersion by 

 a wet thread would take place at the same rate as by 38 inches 

 of a thicker wet string; or that the 38 inches of wet string 

 would disperse equally with a string twelve times its thickness 

 and one-third of its length : water, as everyone knows, has a 

 singular power of dispersion. Nor can it be admitted without 

 proof, that the galvanometer coil in all cases, especially that 

 wherein the discharge of the battery occupied " two or three 

 seconds," transmitted it without overflowing laterally from wire 

 to wire, or from layer to layer, in the manner affirmed by Col- 

 ladon to have taken place in his experiments, and which com- 

 pelled him to use a cod covered with double silk, and with other 

 silk interposed between the layers. Faraday used a galvanometer 

 in which no such precautions were taken : if none such were 

 necessary, why did Colladon fail when a common galvanometer 

 was employed, and why did he succeed when he guarded against 

 lateral communication ? 



One more observation may be made in connexion with these 

 experiments. Faraday endeavoured to maintain the electric 

 machine as much as possible at the same degree of excitation or 

 power during the whole of his experiments with wet strings. On 

 the equality of the power of the machine throughout depended 

 the truth and value of the information conveyed by the galvano- 

 meter ; and a very small change in the excitation of the machine 

 would make a great difference in the amount of the charge com- 

 municated to the Leyden battery. Those who are in the habit 

 of using electrical machines, know how much they are influenced 

 by a number of causes : changes of weather, which sometimes 

 take place within half an hour, alteration of the amalgam by 

 friction, temporary cessation of working the cylinder, difference 

 of rapidity in its revolutions, and other causes, will produce alter- 

 ations of power which will be very manifest in the charge com- 

 municated to the Leyden battery. Every effort was no doubt 

 made to maintain an equal excitation of the plate-machine during 

 the continuance of the numerous experiments ; Imt it is a ques- 

 tion, is it possible to effect this object ? 



These arguments suggest a doubt that Professor Faraday's 

 experiments warrant his inferences. I shall now assign reasons 

 for believing that they lead to inferences of an opposite kind. 

 He conceived that the deflections of the galvanometer are in the 

 direct ratio of the quantity of electricity which pass through it. 

 ilf found that a certain quantity of electricity thrown into eight 

 • I passed through a galvanometer, produced a deflection 

 : and that double the quantity of electricity thrown into 

 fifteen jars causi d a deflection, which, as near as 'the eve could 

 judge, was 1 I , or double the former deflection. The want of the 



