THE GRAPHIC METHOD 87 



ing post provided for convenient electrical stimula- 

 tion. The upper end of the muscle may be grasped 

 in the flat-jawed clamp (Fig. 16), and thus connected 

 electrically with the binding post upon it. 



In obtaining the extension curve of muscle this 

 lever, after-loaded, may be weighted to one hundred 

 grams without bending and thus deforming the curve. 

 The abscissa will be a straight line. The moving 

 parts are very light. The apparatus is compact and 

 occupies but little of the vertical space so valuable 

 where several recording instruments must be placed 

 upon the same stand. 



Writing Lever. A strip of aluminium, bent at 

 one end to fasten with the double hook, pointed at 

 the other, may be used in place of a straw. 



Tuning Fork. A nickelled polished steel fork 

 (Fig. 22) with steel handle is filed until it gives one 

 hundred double vibrations per second. The tuning 

 fork may be provided with a paper or foil writing 



Fig. 22. The tuning fork ; about one-sixth the actual size. 



point and clamped to the iron stand. It serves to 

 measure the latent period of muscular contraction and 

 similar phenomena of brief duration. 



Start the drum at very rapid speed. Bring 

 the writing point of the vibrating tuning fork 



