METHODS OF ELECTRICAL STIMULATION 65 



The Platinum Electrodes. The stimulating elec- 

 trodes are provided with platinum points projecting 

 about 10 mm., polished hard-rubber handle, 7.5 cm. 

 long, and very flexible silk-covered connecting wires 

 G5 cm. long, ending in nickel-plated brass tips (Fig. 

 15). The rubber handle is in two pieces, screwed 

 together, permitting easy access to the connection 

 between the flexible wire and the 

 stiff wire into which the platinum 

 points are inserted. 



The Flat-jawed Clamp. The 

 flat-jawed clamp, or " Femur 

 Clamp" (Fig. . 16), consists of 

 strong, smoothly working brass 

 jaws attached to a steel rod. 

 The jaws are separated by a spring 

 and brought together by a screw. 

 They will hold objects of widely Fig. 15. 



f -i .1 electrodes; about one-third 



varying size, for example, the the actual size . 

 femur of a nerve-muscle prepara- 

 tion or a board a centimetre thick. The clamp has a 

 binding post for making electrical connection with a 

 muscle or other conductor held between its jaws. 



The Round-jawed Clamp. The round-jawed clamp 

 is convenient for holding burettes, tubing, rods, ther- 

 mometers, etc. (Fig. 16). 



The Double Clamp. This is a strong clamp of 

 enamelled iron with two brass nickelled screws (Fig. 

 the coils approach is not linear. An exact method of gradua- 

 tion has been given by Kronecker. 



