26 DIRECT-CURRENT -DYNAMOS AND MOTORS. 
wound. so that there are only two paths through it, being 
called a two-circuit winding (Fig. 16, page 27). 
4. In bipolar or multipolar machines two or more con- 
ductors are often used in parallel to avoid the trouble 
of handling large wires, or in order to fit them into a cer- 
tain space. 
TABLE 13. 
DATA OF BARE AND DOUBLE COTTON-COVERED WIRE 
1 2 3 4 5 6 “sf 8 9 
Area, Number 
-.on. | bs Max. | Number ; Resistance 
Size ees ny hy per | Ohms |Diam. of| of wires of tga per cubic 
Bare | Mils. | foot, | perft.|D. C. C. inch. square inch at 
Wire. Wire D. Cc Cc. D. Cc. Cy 
5 -1819 | 33,124. | .1002 | .000313) 197 5.1 25.8 -000673 
6 1620 | 26,244 .0795 .000394 177 5.6. 31.9 . 0010.0. 
q 1443 | 20,736 .0630 -000497 159 6.3 39.6 -001638 
8 -1285 | 16,384. | .0590 .0006' 148 7.0 48.9 .00256 
9 1144 | 12,996. | .0396 | .000791) .129 7.8 60.2 -00396 
10 .1019 | 10,404, | .0314 | .000992 117 8.5 78.1 -00607 
11 09074 | 8,281. | .0249 | .00126 106 9.4 89.0 -00934 
12 08081 | 6,561. | .0198 .00159 10.8 115.6 -01526 
13 07196 | 5,184. | .0157 00200 084 12.0 145.2 -02410 
14 06408 4 .0124 00252 075 13.3 177 8 -0373 
15 05707 | 38,249 -0099 00818 067 14.9 222.8 0590 
16 05082 | 2,601 .0078 00401 061 16.4 268.7 -0896 
17 04526 | 2,025 .0062 ' 0506 .055 18.2 330.6 1392 
18 04030 | 1,600. | .0049 | 00638 050 20.0 | 400.0 2124 
19 03589 | 1, .0039 00804 046 21.7 473.5 -B172 
20 .08196 | 1.024 0031 .01014 042 23.8 566.9 .4790 
21 -02846 812.3] .00245 | .01275 038 26.3 692.5 7375 
22 .02536 640.1) .00195 | .016C8 035 28.6 876.3 
23 .02257 510 8} .00154 | .02080 -033 80.3 918.3 1.555 
24 .02010 404. | .00122 | .02560 030 33.3 1111.1 2.373 
25 .01790 820.4} .00097 | .038225 028 35.7 1216.4 8.436 
26 01594 252.8] .00077 | .04075 026 88.5 1479.3 5.022 
21. Data for Armature Winding.—The data given in 
the above Table 13. will be found, useful by the stu- 
dent when calculating an armature. The table gives the 
area, diameter, specific weight, specific resistance, the 
number of wires that can be wound in a given space, and 
the resistance per cubic inch of winding for the sizes 
