HISTORY, &c., OF INDUCTION INSTRUMENTS. 



297 



Fig. 78. — Ruhmkorff's induction reel. 



machines, especially when they are furnished with an interrupter 

 for giving isolated discharges at the pleasure of the operator. 



(a). Buhmhorfs hos- 

 pital apparatus. — " IM. 

 Kuhmkoiff has recently 

 arranged a portable ap- 

 paratus, designed espe- 

 cially for hospital use, 

 and in which are com- 

 bined the conditions 

 most essential to secure 

 the regular employment 

 of induction currents. 



"This apparatus (fig. 79) contains two elements of zinc and 

 carbon with bisulphate of mercury ; the zinc can be more or less 

 deeply immersed in 

 the liquid, as a means 

 of graduating the in- 

 ductive effect. One 

 of these elements 

 suffices for ordinary 

 cases; the second is 

 especially as a re- 

 serve. The mode of 

 graduation is by the 

 greater or less inser- 

 tion of one coil within 

 the other, by which 

 the effect can be 

 reduced, if needful, 

 almost to zero. The 

 trembler is that of 

 Neef: and the fre- 



,, . . , Fig. 79.— Ruhmkorff's apparatus. 



quency oi its inter- 

 ruptions can be regulated by means of a screw. A star, moved 

 by a small handle, enables the operator to produce intermittent 

 effects. 



" This instrument gives either the extra current, or the induced 

 current of the first kind." 



(&). BuhmJcorff's portaUe apparatus. — " The same manufacturer 

 has also long made a portable apparatus specially intended for 

 private practice, and which is of much smaller bulk than the fore- 

 going. 



It contains two elements of zinc and carbon with bisulphate of 



