79 



vices have been patented for this method 

 of working ; but the author is not aware 

 that any one of them has proved success- 

 ful. 



2. By the employment of a direct-cur- 

 rent motor with laminated field-magnets. 

 Such motors have been made and tested 

 by various engineers; and about two 

 years ago the author also experimented 

 with such a motor, but the results were 

 discouraging. The work obtainable from 

 this motor, with a given current and 

 electromotive force, was only about one- 

 fifth part that which might be obtained 

 from the same motor if driven by a direct- 

 current of the same measured strength, 

 and flowing under the same pressure. 

 This particular type of motor was, there- 

 fore, commercially, quite unfit for use 

 with an alternating-current supply. After- 

 wards, when investigating the reason of 

 this failure, the author found that the 

 electromotive force of self-induction was 

 far too great, in comparison to the counter 

 electromotive force of the armature, pro- 

 ducing thus a very large lag, and conse- 



