Page:Popular Science Monthly Volume 91.djvu/460

 444

��Popular Science Monthly

��Spark gap- 1

���The operator's set comprises a four-inch spark coil, a manipu- lating key, and a small fixed oil condenser, all in a steel box

��As you might Imagine, the set is small and extremely light. It comprises just a 4-in. spark coil, a manipulating key, a small fixed oil condenser, contained in a steel box, and an aerial coil. This helix or aerial coil is not made of the usual copper tubing, bound on a wooden frame. It is made of several turns of soft flexible insulated wire wound round a piece of wood and kept se- curely in place by two cross-pieces of wood.

The lay-out of the appa- ratus is not necessarily uniform. Usually the airman shifts it to suit his own con- venience, but as a rule its position is this: The condenser and coil are placed under the seat; the aerial coil is made fast to the framework near the operator. The key is on a small wooden shelf fixed to the side of the seat, and sometimes it is placed on a partition in front of it.

In the case of the small scouting ma- chines, the aerial is fixed on the top of the wings and runs round the edge, while the lead-in wire is brought in from the center. Then the earth or ground wire hangs over the side of the plane to the same length and capacity as the aerial. In these cars, of course, the pilot and operator are identical. Only one man goes up.

In the big battleplanes, the aerial is in much the same position. It is fixed to the top. of the top plane. But the ground wire is arranged differently from that on the scout machines. Here it is attached to the bottom of the bottom plane. In other words, there is an upper and lower capacity, just as in the Lodge-Muirhead system.

Now in these planes the operator is the observer. He sits in front of the pilot. But, in case he should be shot or in any way incapacitated,, there is a manipulating key in the pilot's pit joined in parallel to that in the observer's chair, so that either man is in a position to operate.

There is, of course, no receiving ap- paratus. So far it has not been found necessary. For if you are traveling at the rate of 120 or 130 miles an hour, which is the speed many of these planes are able to

��make, it is hard enough to breathe without wasting effort in trying to hear. Besides, even if the rush of air would permit you to collect your senses, there is still the propeller to be reckoned with. The noise of this close to the ear can be compared only with that of a forty-coach express train tearing at top speed through a tunnel.

But suppose it were possible to perfect an

instrument that could make itself heard

against these handicaps, of what use

Glass would it be,

when com- p 1 e t e d ? Under the circum- stances in which the airman fights, in- struc tions from the earth are of nousetohim. He is the one man in the war who fights as an individual. Once he has left the earth with general orders as to the object of his flight, he takes advice and instruction from no one. The thoroughness of his work, the chances of his safety are matters left entirely to himself. They depend solely on individual initiative.

Let me take you with him on a trip, typical of one he might make any morning that is clear enough to let him see what is happening on earth.

��Oil condenser-

���Aerial coil-^

"VL—O'i condenser

���The condenser and coil are placed under the seat and the key on a shelf near by

The artillery has got the range roughly and set their sights accordingly. The air- man ascends, and is soon soaring over the enemy lines. Now he is in sight of the target.

He signals "G" back to the artillery. That means "Go! Commence firing."

They fire. In a couple of seconds there ascends a streak of smoke. To his eye it is no bigger than the puff of a cigarette, but it

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