1885.] NEW YORK ACADEMY OF SCIENCES. 109 



net proportional to the increase of strength of the armature 

 magnet. 



Indeed, it would seem as if he had come very near realizing the 

 ardent desire of all mechanics regarding their machines — "Once 

 in order always in order." For economical reasons, motors run- 

 ning on arc circuits with a constant current, should have other 

 methods of governing than the use of compound reversed coils. 



Mr. Weston uses two methods for obtaining a constant speed. 

 The first is by using belts upon reversed cone pulleys, which, with 

 the aid of a centrifugal governor, shift so as to retain a constant 

 speed for the driven machine, whatever be the variations of speed 

 in the motor. The second is to vary the intensity of the field by 

 means of resistance controlled by a governor or other automatic 

 device. In our equation of condition for a constant speed, we 

 observed two suggested methods of procuring this constant speed. 

 The first was to vary the intensity of the field with the counter 

 electro-motive force. The second was to vary the length of the 

 wire in the armature coils. 



This latter is manifestly impossible with the ordinary forms of 

 machines, although it is not impossible that part of the field 

 might be cut off, or the armature itself partially removed from a 

 constant field. 



Another way is to vary the counter electro-motive force of the 

 motor by shifting the brushes around the commutator, but this 

 is usually productive of sparking, and results in injury to both 

 brushes and commutator. 



The number of variations of this method is legion, and I would 

 only weary you by recounting them. 



For the purposes of locomotion, special arrangements to pro- 

 duce a uniform speed are not required. From all parts of the 

 civilized world we learn the steady progress of the successful 

 application of dynamic electricity to problems of locomotion. 



In the transmission of power by electricity, the ends to be 

 reached can well be stated under these heads: 



(A.) Each receiving apparatus should receive its part of the 

 generated power, and, whatever be its action, should not influ- 

 ence other apparatus on the same circuit. 



(B.) The efficiency must be independent of the number of 

 apparatuses in action. 



(C.) When a regular speed is desired, the regulation should be 

 automatic and instantaneous, and should not require the inter- 

 vention of an attendant. 



Coming, as I do, from almost a year of unremitting experi- 

 mental labor in a very small portion of the field I have this 

 evening attempted to cover in an hour, I can only compare 



