If a conductor be moved by the end of a coil similar to that shown in Fig. 5, when there is a current in the winding of the coil, there will be an electrical pressure induced in the conductor, just the same as though it were moved by the end of a permanent magnet. The polarity of the coil is marked in Fig. 5. The magnetic lines pass from the S-pole to the N-pole through the coil and from the N-pole to the S-pole outside the coil, just as they do in a permanent magnet.
How to Lock a Tenoned Joint
A tenon placed in a blind mortise can be permanently fastened, when putting the joints together, by two wedges driven in the end grain of the wood. In some cases, where the wood to be used is very dry and brittle, it is advisable to dip the tenon in warm water before applying the glue. The glue must be applied immediately after the tenon is removed from the water, and then inserted in the mortise. The sketch shows the application of the wedges. The bottom of the mortise drives the wedges as the tenon is forced in place.
Wedges in Tenon
Fitting a Large Cork in a Small Bottle
When necessary, a large cork may be made to fit a small bottle, if treated as shown in the sketch. Two wedge-shaped sections are cut from the cork, at right angles to each other, as shown in Fig. 1. The points are then squeezed together (Fig. 2) and the end inserted in the bottle (Fig. 3). Wet the cork slightly and the operation will be easier.—Contributed by James M. Kane, Doylestown, Pa.
Reducing Size of Cork (Fig. 1, Fig. 2, Fig. 3)