Page:Popular Science Monthly Volume 91.djvu/814

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��Popular Science Monthly

��the wind. Much better results can be had by using an anchor such as is shown in the illustration, which is practically self -ex- plaining. In Fig. I is shown the cross- section of the L-shaped trench, which should be 5 ft. in length. A 43^-ft. length of 3<£-in. rod is threaded at one end and an

���The trench and manner of placing the anchor for bracing and strengthening the guy-wire

eye is formed on the other end, which is welded at the joint to strengthen it. The rod is then driven in the ground so that it will take the position as shown in Fig. 2. Then a 4-ft. length of 2 by 4-in. stock is bolted on and the trench filled. It is best to place guy-anchors the same distance from the base of the mast as the vertical height of the guy-wire, so that the guy- wire lies at an angle of 45 deg. with the mast. — E. R. Thomas.

��A Magnetic Telegraph Key for the Wireless Operator

THE magnetic key shown in the two accompanying drawings is easy to construct from material usually in pos- session of the experimenter. At the same time it fulfils all the requirements of an expensive magnetic key. It can be used where it is desired to operate the sending set at some distance from the receiving set, the small control key being at the receiver. This obviates the necessity of extending the power wires. This instrument comprises a regular wireless key (I used a Marconi key)

��and a 20-ohm telegraph set. The instru- ment can be constructed as follows:

First remove the small key from the telegraph set. This is to be placed at the operating table, and used as the control key. Remove the arm, anvil, and support from the sounder, thus leaving nothing but the magnets M. Screw the armature A, from the arm of the sounder,' on the under- side of the heavy wireless key-lever where the knob is attached. The knob may be left in place. The next thing is to make a large base about 1 ft. long and about 6 in. wide. Screw on it the base of the telegraph instrument, with the magnets M in the position shown in the drawings. Fit out the wooden block B, bore two holes through it for the lugs of the key, and fasten on the wires that connect the binding posts with the key. If the key you use has no lugs but is fastened down by screws and has the connections on top, it will of course be unnecessary to bore the holes in the block B. The key should, nevertheless, be fastened to block B as shown in the draw- ings. Now with the screws S fasten down the block B, with the key bolted to it. Place enough washers W under the block so that there will be a very small space (about 1/32 in.) left between the magnets M and the armature A when the contact points of the key are touching. The key is now ready for use. It will be found that it works easily and requires little current.

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� ��A magnetic key for use where the sending set is at some distance from the receiving set

It can be regulated so it will work accurate- ly at the highest speed any operator can send, and will handle currents as high as the capacity of the wireless key that is used with it. — R. H. Maxon.

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