250 LOCALIZED ELECTRIZATION. 



use tlie three elements of the battery, for cases in which great 

 power is required, the knob L' should be turned back in the con- 

 trary direction. 



2. If it be desired to obtain rapid intermissions of the trembler 

 A (fig. 52), we turn from right to left the knob C which fixes the 

 movable j)late, and then turn froin left to right the buttons E, G, 

 L, N, so as to bring them into contact with the pieces of platinum 

 to which they correspond. When this is done, the plate oscillates 

 rapidly between the screw S and the temporary magnet of the 

 central coil. 



If intermittences more or less separated from one another are 

 desired, the arrangement is made as before, except that the button 

 C is turned from left to right, so as to render the plate A of the 

 trembler immovable, and the button L from left to right, so as to 

 separate it from its platinum connection. We then connect with 

 this button one of the conductors fixed to one of the knobs, 1, of 

 the pedal rheotome Y, and the other conductor, from the knob 1' 

 of the rheotome, is attached to the button L'. It is then only 

 necessary to govern with the foot the spring contact 2 of the 

 pedal rheotome, in order to make and break contact at pleasure. 

 It is, therefore, perfectly easy to obtain intermissions separated by 

 any desired interval. 



3. When the graduator B is entirely contained within the in- 

 strument, the currents are at the minimum of intensity; and, in 

 order to increase them, it is only necessary to draw out this tube, 

 either by millimetres or by centimetres. 



4. The apparatus being in action, the conductors must be fixed 

 to the knobs P and Q, to which, according to the indications to be 

 fulfilled, we bring the current of either the primary or of the 

 secondary coil, by turning to the right or the left the needle of 

 the commutator. To the free extremities of the conductors are 

 attached the rheophores, cylinders, metallic brushes, &c, &c. 



5. If it be desired to faradize very excitable organs, or to 

 measure infinitely weak doses, the upper part, K, of the moderator 

 r must be connected with one of the knobs P or Q, and one 

 of the rheophores with the lower part of the moderator I. Then, 

 the more we draw up the stem J of the moderator, the greater 

 will be the thickness of the water traversed by the current, and 

 the more the latter will be weakened. The current may then be 

 divided and measm*ed by the tube graduator B. 



6. In the intervals between faradizations, we interrupt the cur- 

 rent by turning back the screw E, so as to preserve the force of 

 the pile. At the same time, plates of hard caoutchouc must be 

 placed between the cloth and the zinc, care being taken to wipe 



