To obtain the interrupted galvanic current, move the switch at left of selector on to button marked interrupted, then turn the switch just above the vibrator on to its button marked 11, by adjusting the screws at 14 and 15 the proper degree of vibration will be obtained. It is necessary that the point of the screws at 15 should touch the plate with every vibration as the current passes through at this point and unless it touches, connections would not be made.
TO MEASURE THE RESISTANCE OF THE PATIENT.
To measure the resistance of the patient turn the lever at the left of selector on to the button 8 marked milli-ampere-meter and wire rheostat. Supposing him to have the electrodes in his hands and a current from 30 cells registers 8 milli-amperes; without changing any other conditions, throw the upper left-hand lever 10 on button marked rheostat and milli-ampere-meter only. The patient will now be thrown out and the needle will fly around as far as it can go.
Begin by throwing in resistance, which is done by manipulating the top row of levers, until the needle which will have retraced its course rests directly over the division marked 8 milli-amperes or whatever may have been the previously recorded amount. The numbers on uncovered buttons added together will be the resistance of the patient. The known resistance having taken the place of the patient.
The upper left-hand lever should at all times except for purposes of measuring the resistance of a patient, be kept on its blank button, or the battery will be short circuited and injured.
THE POLE CHANGER.
The pole changing lever above the two posts marked 13-13, when pressed between the two right-hand springs makes the right-hand binding post positive, and when pressed between the two left-hand springs the left-hand post becomes positive and the right negative.
GRAPHITE RHEOSTAT.
When the left-hand lever is placed on button 9 it throws the graphite rheostat (16) into circuit. To use the rheostat first draw up the rod (17). By slowly pressing the rod down through the graphite it gradually lessens the resistance thereby increasing the current without shock to the patient. With this rheostat you can place any number of cells in the circuit.
THE DE WATTEVILLE SWITCH.