ALTERNATING MOTORS FOR RAILWAY WORK. 167 
distinct fields of usefulness in electric lighting—why not 
also in electric railroading ? 
Out of the motley throng of alternating motors four 
typesare fairly promising for application to railway practice. 
Each is characterized by a combination of good and bad 
qualities somewhat difficult to evaluate in the present 
state of our knowledge of alternating railway work. We 
may tabulate the types in question as follows: 
I. Synchronous motors started by commutation, 
II. Synchronous motors started as induction motors. 
III. Asynchronous polyphase motors. 
IV. Asynchronous monophase motors. 
The first two classes have exceedingly valuable properties 
for certain purposes, but are not suited for railway work 
requiring very frequent stopping and starting or constant 
variation of speed. 
The third class can meet all requirements as to starting 
torque and speed variation, and can be made substantially 
as efficient and durable as continuous current motors, but 
requires a somewhat troublesome system of working con- 
ductors. 
The fourth class starts sufficiently well, is somewhat 
weak at present in the matter of speed variation, but can 
be operated on existing systems of working conductors. 
I. It is a well known fact that a series wound motor 
with fields laminated to check eddy currents will start and 
run fairly well on an alternating circuit, particularly if the 
frequency is low. = The late Mr. Fickemeyer produced a 
motor of this class which gave admirable starting torque 
and ran with a good degree of efficiency. The practical 
difficulty that has hindered the commercial development of 
such motors is rather severe sparking, which seems to be 
irremediable and if long continued does serious damage to 
the commutator. 
If, however, the sparking only occurs during the pro- 
cess of starting it is not a difficnlt matter to avert injury to 
the commutator, so that if such a motor can be worked 
normally as a synchronous alternating machine, and as a