Page:Book of record of the time capsule of cupaloy (New York World's fair, 1939).djvu/47



HOUGH in all probability methods more sensitive than any we have today will be employed in the future to seek for metallic bodies beneath the earth, it is possible, too, that this will become a lost art. It is therefore suggested that the Time Capsule may be discovered by detecting the secondary electromagnetic field induced in it by a strong primary electrical field created at the surface of the ground.

Construct a loop some ten feet in diameter, composed of several turns of well-insulated wire, fashioned in such a manner that it can be moved systematically over the area within which the Capsule is believed to lie. While the loop stands vertically, pass through it an alternating current of 1,000 to 5,000 cycles, using a power source of 200 watts. The primary electromagnetic field thus set up around the loop will intersect any metallic material in the vicinity, such as the Capsule, and will induce in it a secondary current. This current will produce a secondary electromagnetic field such as will distort the primary field of the "energizing" loop. This distortion, properly interpreted, will indicate the location of the Capsule.

To investigate this phenomenon, construct a second, smaller coil, approximately a foot in diameter, made up of a large number of turns of insulated wire. To the coil