798 



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. 



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. 



