METHODS OF ELECTRICAL STIMULATION 43 



The Long Rheochord. In the long rheochord 

 (Fig. 6) a metre rule is screwed upon a wood 

 base. At each end is a binding post. To post is 

 fastened the end of an unbroken German-silver wire 

 twenty metres in length. This wire is carried along 

 the metre stick to the second .post, 1, then wound 

 upon a spool, and the end fastened to a third binding 



Fig. 6. The long rheochord ; about one-thirteenth the original size. 



post. The wire upon the metre rule is bare, the 

 remaining nineteen metres silk-covered. A conven- 

 ient spring contact with binding post slides along the 

 metre rule. 



The Square Rheochord. Upon a block of hard 

 maple, 12.5 cm. square, is placed a centimetre scale 

 beginning at the 0-post shown on the left side of 

 Fig. 7 and ending at the 1 -metre post visible in 

 the background to the left. For the sake of clearness 

 the numbers on this scale have been omitted from the 

 figure. Along the scale, between these two posts, is 

 stretched the first metre of a continuous German-silver 

 wire, 0.26 mm. in diameter and twenty metres long. 

 The remaining nineteen metres of this wire are coiled 

 upon a spool, and the free end is fastened to the 

 twenty-metre post shown in the background to the 

 right of Fig. 7. One of the posts may be turned, in 



