Two supports, each 1/2 in. thick and 3 in. high, are fastened with screws about half way between the end of the base and the upright B, Fig. 1.  The end view of these supports is shown in Fig. 2, at GG.  A 1/8-in. hole is bored through the top part of each support so they will be in a line for the axle.  The axle is made of a piece of steel 1/8 in. in diameter and about 4 in. long.  An offset is bent in the center, as shown, for the crank.  A small flywheel is attached to one end of the shaft.  The connecting rod E, Fig. 1, is made of wood and fastened to the upper end of the driving arm D with a small screw or nail.  The contact F is made of a strip of copper, 14 in. wide.  This is to open and close the circuit when the engine is running.  The connections are made as shown in Fig. 1.

Connect two dry cells to the binding-posts and turn the flywheel.  The current passing through the magnet pulls the driving arm toward the bolt head, which gives the shaft a half turn.  The turning of the shaft pulls the arm away from the copper piece F, causing a break in the current.  As the shaft revolves, the arm is again brought back against the copper strip F, thus the current is broken and applied at each revolution of the shaft. —­Contributed by S. W. Herron, Le Mars, Iowa.

** Child’s Home-Made Swing Seat [276]

A very useful swing or seat for children can be made from a box or packing case.  Procure a box of the right size and saw it out in the shape shown in the illustration.  The apron or board in front slides on the two front ropes.  The board can be raised to place the

[Illustration:  Made of a Box]

child in the box and to remove him.  The ropes are fastened to the box by tying knots in their ends and driving staples over them.

** Clay Flower Pots Used for Bird Houses [277]

A novel use of the common garden flower pot may be made by enlarging the small opening at the bottom with a pair of pliers, and carefully breaking the clay away until the opening is large enough to admit a small bird.

Place the pot, bottom side up, on a board, 3 in. wider than the diameter of the largest pot used, and fasten it to the board with wood cleats and brass screws.  Fit the cleats as close as possible to the sides of the pot.  One or more pots may be used, as shown in the sketch.

The board on which the pots are fastened is nailed or screwed to a post or pole 10 or 12 ft. in height.  The board is braced with lath or similar strips of wood, making a framework suitable for a roost.  In designing the roost, the lath can be arranged to make it quite attractive, or the braces may be of twigs and branches of a tree to make a rustic effect.  —­Contributed by William F. Stecher, Dorchester, Mass.

[Illustration:  Pots Fastened to the Board]

** Location of a Gas Meter [277]

The gas meter should not be located in a warm place or the gas will expand before the meter measures it and the gas bill will be proportionately increased.  Gas expands by about 1/491 part of its volume for each deg.  F. that it is heated.  If the meter is warmed 10 deg.  F., it will make the gas cost over 2 per cent more, without any corresponding benefit.