A SYNCHRONOUS MOTOR KYMOGRAPH 321 



entirely feasible, however, to design a base with slots for bolting 

 the motor to it, and mount a series of worm-wheels on the 

 horizontal shaft, so that by sliding the proper wheel into position, 

 and moving the motor into its proper position for that wheel, 

 any of the speeds corresponding to the series of worm-wheels 

 may be employed. 



The kymograph may also be designed to run with a vertical 

 drum, but in this case the drum could not be so simply removed 

 and replaced as in the present instrument. 



The drum-shaft rotates on bearings Ji and / 2 , which I have 

 designed especially for this mechanism. Each bearing consists 

 of three screws with polished hardened ends on which the shaft 

 rests. By adjusting these screws, which are provided with 

 lock-nuts, the drum-shaft may be lined up accurately with the 

 worm-wheel shaft. When the current is off the clutch magnets, 

 the drum may be lifted out of the bearings without the un- 

 fastening of any catch, and it is as easily replaced. 



The writing levers used with the present kymograph are 

 mounted on a heavy iron block, with planed self-cleaning grooves 

 sliding on planed guides on the base (not shown in the cut). 

 For work where records occupying not more than one drum- 

 rotation are required, this is the ideal system. The block may 

 be slid to any desired lateral position, which it will keep without 

 fastening: and it may be slid to the left far enough to remove 

 the writing from the drum, and allow the latter to be lifted out. 

 A mechanical shift of the carrier, for spiral records on the 

 drum, could be arranged. The instrument can also be designed 

 to use continuous paper. 



For the satisfactory driving of a small synchronous motor of 

 the type used in this kymograph, platinum contacts should not 

 be used on the fork. Dental wire, of gold hardened by alloy 

 with platinum, is best for the moving part of the contact, 

 attached to the fork tine, and a plate or stud of the same alloy 

 should be used for the fixed part of the contact (although platinum 

 is satisfactory for this part). I have found that a short section 

 of large gauge wire, set in the end of the adjusting screw, is a 

 satisfactory arrangement for the fixed part of the contact. 



