Fig. 15.—A primitive electro-motor.

A.Square of copper or tin.
B.Brass standard.

Fig. 16.—Standard for electro-motor.

Next plug the center hole of this reel with hard wood, and bore another hole through of smaller diameter, so as to slide stiffly on a straight piece of 1⁄8-inch brass wire. About 1 inch from the cotton reel is to be soldered a 3⁄8-inch square of tin or copper sheet, having a hole at its center through which the brass spindle passes ([Fig. 16]). Two small brass standards, for which straightened curtain-rod clips may well be employed, are screwed about 31⁄2 inches apart to a wooden baseboard, and have a hole drilled near their top edges to accommodate the spindle (B, [Figs. 16] and [17]). This being placed in position, should be provided near the bearings with washers (E, [Fig. 17]) and beads (D, [Fig. 17]), the washers being soldered in order to prevent lateral movement of the shaft. Lastly, with a view to realistic appearance, solder a small tin fan (C, [Fig. 17]) to one projecting end of the spindle, and enamel or paint it gray. The arrangements of these fittings are made quite clear by the diagram.

Fig. 17.—An electro-motor.

H.Wood strip across top of magnet.
I.Block of wood supporting bobbin at correct height.
J.Wood base board.

Fig. 18.—Bell-bobbin mounted.