32 .DIRECT-CURRENT DYNAMOS AND MOTORS. 
number of inductors, N, on a smooth-core armature can 
therefore be obtained from : 
os 'visis teal 
In toothed armatures, the slots usually take up about 
one-half of the circumference, and only about three-fifths, 
or .6, of the total slot area is actually occupied by the in- 
ductors, approximately one-fifth of the slot area being 
TABLE 14, 
AVERAGE HEIGHT OF WINDING SPACE ON ARMATURES, 
Approximate Height of Winding Space, h,. 
Diameter of P ' 
Armature, in Smooth Armature Core. 
Inches. 
D. Toothed Arma- 
sii ture. 
Drum. Ring. 
9” }’ ve ma 
+ #5 32 a 
6 $ t $ 
10 2 bs i: 
15 g 
20 3 $ 14 
30 t ay 13. 
50 4 13 
15 vs % 2 
100 ss 3 24 
150 $ 34 
200 1 4 
used up by the slot lining and about one fifth of it by the 
wire insulation. Hence, the approximate total number 
of inductors is: 
5 X.69, 8X Dek OMe Dee Ma 
N= BG SM EN AD) 
The figures obtained by (16) and (1'7) should be checked 
by means of Table 13, as shown in Par. 22, 
