SMALL DOUBLE-CUREENT VOLTA-FARADIC APPARATUS. 267 



Fig. 62. 



Fig. 63. 



Fig. 60. — Author's small volta-faradic apparatus (opened). 

 Fig. 61. — Details of the cover of the compartment to the right. 

 Fig. 62.— Pedal. 

 Fig. 63. — Pair of elements with bisulphate of mercury. 



a millimetre in diameter, and the wire of the secondary coil is 

 three hundred metres in length and a sixth of a millimetre in 

 diameter) ; 2, of a core formed by a broad band of soft iron rolled 

 into a helix, as in fig. 59, so that it can be placed in the centre 

 of the reel ; 3, of a commutator of the coil, C (all the foregoing 

 portions are concealed in the compartment to the right) ; 4, of a 

 graduator tube D ; 5, of a trembler E, and of a rheotome L for 

 slow intermissions. 



B. — Manner of jputting the apj^aratus in action. 



A pair of elements with bisulphate of mercury (fig. 63), like one 

 of the pairs of my large apparatus, is introduced into the com- 

 partment A. Then if the door G of this compartment be closed, 

 as in fig. 58, the small platinized plate L' (fig. 63), which com- 

 municates with the carbon contained in the caoutchouc cell, 

 comes in contact with the spring H, which rests against the plati- 

 nized termination F of one of the extremities (poles) of the primary 

 coil, while the zinc N (fig. 63) is brought into communication with 

 the other extremity (pole) of the primary coil, by the spring H'. 

 The separations of this electro-motor from the coil are produced 

 by the separation of the horizontal bar E (fig. 60) from the knob I. 



