This is a most remarkable bull-pup for he will jump out of the kennel when you or any one else calls him, when you clap your hands or on any other occasion when a loud noise is made.

Always make a dog-house for a pup before you catch him so that when he gets home he'll know he's there. Use smooth 1/2 inch thick pine boards for the house and cut out a piece 7 inches wide and 8 inches long for the floor. Cut a slot clear through the board 1 3/4 inches from one end and parallel with the edge of the back and have it 1/2 an inch wide and 1 1/4 inches long; then on each end of the slot cut a groove 1/2 an inch long and 1/4 inch deep as shown at A in Fig. 105. Cut out two pieces for the sides of the house 4 inches wide and 8 inches long and screw them to the floor. Now bevel off the top edges of the sides with a plane to allow for the slope of the roof but before you put it on you must install the wireless apparatus that makes the pup jump out of the dog-house. Make a back out of a board 7 inches square as shown at B.

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Fig. 105B. The Back End Of The Dog House

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Fig. 105C. The Spanker With Electric Solenoid Control

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Fig. 105D. Cross Section Side View Of The Wireless Pup Ready For Action

This apparatus consists of five chief parts and these are (1) a spanker; (2) a solenoid; (3) a stiff piece of clock-spring; (4) a telephone transmitter and (5) two or three cells of dry battery.

The spanker, so called because it spanks the pup out of his kennel, is shown at C; it is simply a strip of wood 1/8 inch thick, 1 inch wide and 3 1/2 inches long. Tack, or otherwise fix, a piece of tin to one side of it to form an electrical contact; cut a 3/8 inch hole in the middle of it and then drive a brad in each edge near one end. The spanker sets in the slot in the floor and the brads rest in the grooves and serve as pivots. A solenoid is merely an electromagnet with a loose iron core in it. Make a cardboard spool 1 1/4 inches long and 1 1/2 inches in diameter and have the hole in it 7/16 inch in diameter; wind it full of No. 20 or 22 double cotton covered magnet wire and your solenoid is done. An iron bolt % inch in diameter and 1 1/4 inches long makes a good plunger, as the loose iron core is called. Slip it through the hole in the spanker and screw the solenoid to the inside of the back of the house as shown in the cross section drawing at D.

Make a contact plate of a strip of tin or sheet brass and screw this to the floor back of the spanker so that when the plunger is drawn into the solenoid and the spanker is back as far as it will go the plate will come in contact with the tin on the spanker. Put a stop in front of the spanker to prevent the latter from falling too far forward.

Next get a strong, stiff piece of clock-spring, punch two holes in one end and screw it to the back of the house near the top, with the free end of the spring pressing out the spanker. Fasten by means of hangers, or otherwise, an ordinary telephone transmitter to the roof of the house as shown at D. Now make the front of the house and cut a 4 x 5 opening in it for the pup to get in and out, and a hole 1 1/2 inches in diameter, as shown at E, so that when you put the front on, the hole will be directly over the mouthpiece of the transmitter.

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Fig. 105E. The Front End View Of The Wireless Pup House

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Fig. 105F. When You Call The Wireless Pup Or Clap Your Hands He Comes Out Of His Dog House In A Hurry

Before putting on the front connect up the apparatus as shown at D, that is, connect one of the wires of the transmitter to the contact plate; join the other wire of the transmitter to the battery; lead one of the wires of the solenoid to the tin on the spanker. When these connections are made the circuit will be complete if a battery is connected in and the spanker is pushed back. Now put on the front of the house and then make the pup.

Saw the body of the pup and his legs out of separate pieces of wood and glue them together. He should be 2 3/4 inches high and 5 inches long when done and he must slide easily on the floor. See F, Fig. 105.

The action of the wireless pup is like this: You push the pup into the house and back against the spanker as far as he will go; this presses the spring back and at the same time makes connection with the contact plate which closes the circuit.

The current from the battery then flows through the solenoid and transmitter and this magnetizes the iron plunger core and holds the spanker back against the force of the spring.

If now you call loudly, or clap your hands, the carbon granules in the transmitter will vibrate and this will suddenly weaken the current, and, hence, the magnetism of the solenoid. The instant the magnetic pull of the solenoid is weaker than the spring the latter will force the spanker against the posterior end of the pup's anatomy and boost him out of his kennel.