282 LOCALIZED ELECTRIZATION. 



faradic apparatus ; and have thus rendered it available in every 

 case. The mechanism is extremely simple, and need only be 

 described, to show its utility and necessity. 



The action of the regulator of intermissions, D (fig. 64), should 

 be combined with that of the regulator of the rheotome B. The 

 former is so arranged as to produce a very rapid intermittent cur- 

 rent, and the second so as to touch the four teeth of the rheotome. 



If, on the contrary, the intermissions are to be produced but 

 slowly, the spring of the rheotome should touch only the two 

 teeth of the rheotome B. The following is the reason. While 

 the spring touches one of the pins of the large wheel, the contact 

 sometimes lasts a little too long ; and it may happen that two or 

 four inductions are produced, in rapid succession, at the moment 

 of contact, according to the position of the rheotome : if the latter 

 touches the four teeth, the four inductions which are then pro- 

 duced excite a more powerful sensation ; if, on the contrary, the 

 spring touches but two teeth, the inductions will not be sufficiently 

 near together to occur at the moment when contact is produced 

 with one of the pins of the large wheel. The slow intermissions, 

 and the sensations which they produce, will then be more regular. 



D. — The Oraduator of the Currents. 



The graduating tube of my magneto-faradic apparatus measures 

 the electric doses as exactly as in the case of the volta-faradic 

 apparatus. The details which I have already given with regard 

 to the latter, render it unnecessary to enter into the question 

 anew. 



This system of graduation is the only one by which we can 

 administer to all organs electric doses, proportionately to their 

 degree of excitability, which, as I have shown, is extremely variable. 

 It may be asked, however, whether the initial force of magneto- 

 faradic instruments does not itself vary so much as to render 

 fruitless the employment of any equal measure ? It is established 

 that a magnet, after being subjected to much traction or friction, 

 almost completely loses its power to sustain a given weight. Does 

 this weakening diminish also, in the same proportion, the power of 

 induction? I have related, in the earlier editions, experiments 

 which seemed to answer both questions in the negative. 



E. — The Moderator of the Currents. 



In the magneto-faradic instruments, as in the volta-faradic, the 

 graduating tubes do not entirely neutralize the currents of the 

 coils they cover. It follows that they would be inapplicable to 



