[Illustration: FIG 1. IMPROVED SPRING TRACTION ENGINE.]

[Illustration: FIG. 2]

* * * * *




TABLE SHOWING THE RELATIVE DIMENSIONS, LENGTHS, RESISTANCES, AND WEIGHTS
OF PURE COPPER WIRE.


DIAMETER | AREA
|
B.W.G Inch. Milli- | Circu- Square Square
No. metres | lar inches. Milli-
| Mils. metres.
|
0000 .454 11.5313 | 206116 .161883 10.4435
000 .425 10.795 | 180625 .141862 9.152
00 .38 9.6518 | 144400 .113411 7.3165
0 .34 8.6358 | 115600 .0907922 5.8573
1 .3 7.620 | 90000 .070686 4.5602
2 .284 7.2134 | 80656 .0633472 4.0867
3 .259 6.5784 | 67081 .0526854 3.3989
4 .238 6.0451 | 56644 .0444881 2.8701
5 .22 5.5879 | 48400 .0380133 2.4523
6 .203 5.1561 | 41209 .0323655 2.088
7 .18 4.5719 | 32400 .0254469 1.6417