ALTERNATING GENERATORS AND SYNCHRONOUS MOTORS. 101 
and 4 and 1 belong to the equipolar magnet system of 
the inductor type generator. 
The data in column 4 is based on the supposition, that the 
width of the slot winding and coil breadth ratio is zero. 
This, however, does not comply with the actual case, but 
still the data is sufficient for practical purposes. 
Fias. 56, 57 AND 58.—SINGLE-PHASE WINDINGS. 
The somewhat lengthy method of determining, graphically, 
the form of magnetie¢ field from which the E. M. F. wave 
form is derived, is only of importance in such a ease in. 
which the intention of a designer is to utilize the material 
to the utmost limit, which of .course leaves no margin for 
discrepancies. 
It should be intimated at this point, that it is not desirable 
to drive the design up to the limit of practical calculations. 
177. Reasonable Pole Are Ratio.—Table 14 indicates 
clearly, that the smaller the pole are ratio, the larger the 
form factor; it is misleading to conclude that it is favor- 
able to work with small pole ares. Generally speaking, 
any decrease in the pole are effects an increase in the 
form factor and also improves the leakage conditions, but 
otherwise it diminishes the area of the air section, which 
is larger than the increase of the form factor. 
