HOME. HANDICRAFT 353
Next in importance to a high, long, and well-insulated aerial is the ground, and there are several ways of getting a pretty good one. The first way is to use the gas or water pipes and to solder a No. 6 bare copper wire to it, or fasten it on with a ground clamp; another way is to drive a piece of iron pipe into the ground deep enough to reach moist earth, but the best way of all is to solder a copper wire to a sheet of copper, or zinc, three feet wide and four feet long and bury it deep into the moist earth.
To make an aerial a safety device rather than a source of danger from lightning it should be grounded, when you are not sending or receiving, through an aerial switch. This switch is screwed to the outside of your operating room near the window where the aerial and ground wires go through to the inside.
The Sending Apparatus
To send messages you will need the following pieces of apparatus : (1) an induction coil, or better, a transformer, (2) a telegraph key,. (3) a spark-gap, (4) a battery, or if your house is wired you can tap the circuit and get your current from that source, (5) a tuning coil, and (6) a condenser.
The purpose of an induction coil is to change the direct current of a battery or lighting circuit into high pressure alternating currents. A transformer is used where alternating current only can-be had. A transformer is better and cheaper than an induction coil, having the same sending range and should be used if you can get alternating current to work it with.
The purpose of the telegraph key is to break up the battery or lighting current which energizes the primary coil of the induction coil, or the transformer, into dots and dashes representing the letters of the alphabet, or International Morse Code as it is called. The key is connected in circuit with the primary of the coil and the battery or other source of current.
From the battery or power circuit the power to operate