A SYNCHRONOUS MOTOR KYMOGRAPH 



KNIGHT DUNLAP 



From the Psychological Laboratory of the Johns Hopkins University 



The instrument herein described was constructed in the 

 physics workshop of the Johns Hopkins University from my 

 specifications, and has been in successful operation. It will 

 probably be put on the market, as soon as arrangements can be 

 made therefor, by C. H. Stoelting. 



The instrument consists essentially of a horizontal cast iron 

 base, M y on which are mounted a ten-pole synchronous motor, 

 of the type used in the chronoscope previously described 1 by me ; 

 a drum, L, with magnetic clutches, FI and F 2 , of the type de- 

 signed by me and used on the chronoscope; and a worm-wheel, 

 E mounted on a short shaft. 



The motor is mounted with the armature, C, in the horizontal 

 plane, a worm, D, is cut on the armature shaft, which is of steel, 

 and this worm engages the worm-wheel, E. The shaft of the 

 worm wheel carries the core of the clutch-magnet FI, the core 

 having at its outer end an expansion GI, with flat annular external 

 surface. The armature, and worm wheel and shaft are intended 

 to rotate continuously, the drum remaining at rest until electric 

 current is sent through the windings of the clutch-magnet, FI, 

 from the terminals Oi, whereupon the expansion of the core, Gi, 

 adheres to the disc, HI, mounted on the drum-shaft, and the 

 drum-shaft and drum rotate with the worm-shaft. Upon the 

 breaking of the circuit through the windings of the clutch-magnet, 

 the drum comes to rest, without disturbing the rotation of the 

 armature and the worm-shaft. 



If desired, current may be applied to the breaking clutch- 

 magnet, F 2 , at the moment in which the current through FI is 



1 Journal of Experimental Psychology. 



319 



