and Laboratory Methods. 



2483 



Kahn, R. H. Die Biirstenwippe. Centralbl. f. Kahn has devised a new electric key 

 Physiol, 17: 34-38, 1903. g^^^j current reverser for use in physi- 



ological experimentation, which has certain advantages over forms now in use. 

 The instrument is shown in plan in Fig. 1, and in perspective in Fig. '2. It is 



^>^/ ■•. 



made by J. Krusich, Universitatsmechaniker, in Prag. In the center of a hard 

 rubber plate about 80 mm. in diameter are two metal brushes l> h and b^ l\, 

 isolated from one another by a block of hard rubber. The ends of the brushes 

 are raised from the horizontal, so that when one end makes contact the contact 



Fig. 2. 



at the opposite end is broken. The ends thus have a range of movement of 

 25°-30°, When either end is depressed it makes, on account of the spring in 

 the brushes, a firm contact with one set of metal blocks, either k-k or k^ k^- 

 /C'j-/('2 as the case may be. Movement of the brushes is brought about by 



