Each month Amateur Work magazine reviewed various mechanical and electrical projects for the home experimenter. In its debut issue, the Electrical section included a review of how to construct a radio transmitter and receiver similar to what Heinrich Hertz had used in his famous experiments. Because it didn't include any of the refinements which Guglielmo Marconi had recently developed -- other than a ground wire on the receiver -- this particular setup would have been mainly useful for demonstration purposes, as it was only capable of transmitting a few hundred meters at best.
Amateur Work, November, 1901, pages 4-5:
IF a stone be thrown into a pool of still water, the motion of the stone causes a disturbance on the surface of the water. Circular waves radiate from the point at which the water was struck, diminishing in height until no longer visible. The movement of these waves is slow; the eye can easily follow them and count the number of waves per minute. Other waves in a more elastic medium than water are found to be much more rapid in movement. The striking of a bell causes it to vibrate, which vibration imparts wave motion to the surrounding air. Our ears are so constructed that this wave motion, if the rate be not less than 16 nor more than 44,000 per second, is transmitted through the tympanum and nerves of the ear, and we become sensible of it as Sound. Certain bodies are responsive to a particular rate of vibration. If a violin be played close to a wine-glass in exactly the same tone as the vibration rate of the wine-glass, the wave motion from the violin will set up a vibration in the glass, sometimes so violent as to cause the glass to break in pieces. Many interesting instances of this harmony of vibrating rate are recorded in the various textbooks on Physics.
Sound waves, while much more rapid than the water waves, are still comparatively slow when we consider the rapid vibrating motion of heat waves. The rapidity of these waves is beyond the ability of the mind to comprehend except by comparison. That degree of heat termed "bright red" requires the atoms of the body giving out this heat to vibrate at the rate of 400 billion times per second. It has been discovered that, under certain conditions, electrical waves radiate through space and have the power to influence suitable objects prepared for that purpose. The particular form of electrical wave under consideration is that known as Hertzian waves, so termed from the comprehensive discoveries of Dr. Heinrich Hertz, of Carlsruhe and Bonn. By means of a series of masterly experiments based upon certain phenomena previously discovered by other scientists, Dr. Hertz, between the years 1886 and 1891, added greatly to the knowledge of these electric waves and their effects on adjacent bodies, enabling them to be put to practical use in wireless telegraphy.
These Hertz waves do not have the extremely rapid vibratory rate of heat waves, though, as compared with sound waves, they are still very rapid, their vibrations being, as near as has yet been discovered, approximately 230 millions per second. These waves are set up by any sudden electric discharge, such as lightning flash, or in a less degree by a spark from a sparking, or induction coil or Leyden jar. They are made evident to our senses by suitable apparatus that, being adjusted to the same rate of vibration, receives the wave impulses and acts in unison with them. We may soon be able to learn of the approach of electric storms by means of instruments that will receive the electrical waves set up by the distant lightning flash.
The apparatus for demonstrating electric-wave action is simple and may easily be constructed at small cost. Procure two sheets of heavy zinc 16" square, and mount them in a light wooden frame. Small picture-frame moulding makes a neat-looking frame. At the center of one edge of each plate ( Z ) solder an L-shaped strip of zinc, the projecting piece being about ½" long, and having a 1/8" hole through it. To one end of two pieces of brass wire 4" long and 1/8" in diameter, fit brass balls ( C ) 1" in diameter. The other ends of the wire are then put through the holes in the zinc angle-piece, and when the plates are placed in line, the two balls will face each other. The plates should also be fitted with ebonite or glass feet, raising them 2½" or 3" from the level. At the outside of one plate and in the lower outside corner of the other, bore small holes, and connect, by soldering, two pieces of insulated copper wire, size 16 or 18, which are to connect with the Leyden jar. This Oscillator, as Dr. Hertz named it, if placed on a stand with the plates in line and the balls from ¼" to 1" apart, according to conditions, will, when connected to the outer and inner coatings of the charged Leyden jar ( L ), set up powerful electrical or Hertz waves in the surrounding medium at the instant the discharge takes place between the balls of the "oscillator" plates.
These waves are taken up and made evident by a simple form of receiver known as Hertz's Resonator. This consists of ¼" brass rod 5 feet long bent into the shape of a nearly complete circle 18" in diameter. The unconnected ends are fitted with two 1" brass balls; the distance between them is adjusted by bending the rod. Wings of thin sheet copper 6" wide and 10" long are fastened to each side of the rod by twisting around the rod extension strips that were left on the wings when they were cut out. In place of the brass balls the ends of the rod may be turned into two small circles, and soldered to make a perfect joint. The brass balls are the best, and should be polished with emery-cloth before trying experiments. The circular brass rod ( D ) is held suspended by two round pieces of wood 8" long and 1" thick, the lower ends of which rest in holes bored in the base ( B ). Two round-headed brass screws on each upright hold the brass rod in place, one screw on each side of the rod. It will add materially to the success of the experiment if one wing is connected by a piece of covered copper wire to a "ground." The nearest gas or water pipe will answer. The base is a heavy block of wood with wooden uprights, upon which to fasten the circular rod.