Wireless:The Early Years

THE EARLY YEARS, 1800 - 1860

Two developments in basic electrical science paved the way for experiments in wireless. The first was Italian Allesandro Volta's "pile," an electro-chemical battery, which he invented at the close of the 18th century. With a reliable and constant supply of electrical current, electricians could multiply experimental designs many fold. The second development was the discovery of induction, attributed jointly to England's Michael Faraday and to an American, Joseph Henry, in the early 1830's (Meyer,1971, 64-65; Skilling, 1948, 108-138).

Throughout the 19th century, most wireless experiments and inventions concentrated on two technologies, conduction and induction. In the first case, the electrician hoped to replace the conducting wire in a circuit with either the earth, water, or air. In the second, the plan was to interrupt (in a telegraph system) or modulate at audio frequencies (in a telephone system) the current which passed between the active and passive coils of the induction circuit. In both cases, the inventor had also to build a detector to receive the signal at the other end of the circuit.

The two earliest experiments in wireless conduction took place in Germany. In 1811, Prof. S.T. Sömmering of Munich substituted wooden tubs of water for insulated wire to conduct a telegraph signal a short distance across his lab, but lacked a detector adequate enough to study the results of the experiment. So he abandoned the idea. But in 1838, Prof. Carl A. Steinhill, also of Munich, discovered that he could use the ground to replace one wire as the return in a telegraph circuit. Further experiments proved that he also could use the ground as a primary circuit, deflecting a galvanometer needle some 50 feet away (Blake, 1928, 7; Hawks, 1927,63-66).

In America, Samuel F. B. Morse faced a problem common to all early telegraph engineers -- how to get a signal across a body of water. Cables of that era were brittle, poorly insulated, and likely to be cut by passing ships. Morse devised a system in 1842 which used the water itself as both the primary and return circuits, as illustrated in Figure 2. He tested it across a canal near Washington DC. Later, Morse's assistants, Vail and Rogers, tested this conduction design at Havre de Grace, Maryland, across the Susquehanna River, a distance of nearly one mile. On one bank, Morse sank two metal plates connected by a wire in circuit with a battery. On the opposite bank, he sank two similar plates connected in circuit with a galvanometer. By turning the battery circuit on and off with a telegraph key, he caused deflections in the galvanometer. The strength of the current was directly proportional to the size of the plates and the length of the conducting wire between each pair (Fahie, 1899, 10-13; Hawks, 1927, 73-75). There is no evidence that Morse put this wireless telegraph to general use, but electricians would use variations of his technique for another half century.

Joseph Henry's induction experiments involved wireless communication. At a demonstration before the American Philosophical Society in 1842, Henry excited the primary induction coil with a single spark from an electrical generator. The induced current magnetized a needle attached to the secondary coil some 220 feet away, proving that electrical sparks pervade space and exert inductive effects at indefinite distances (Meyer, 1971, 67). Four years later, Henry became the first director of the Smithsonian Institution. With the introduction of the more powerful induction coil by German Heinrich Ruhmkorff in the 1850s, Henry's basic research would have profound impact on electricians in the latter part of the century.

Of final interest during this period was the work of Scotsman James B. Lindsay. A telegrapher with a dream of building a system to communicate with America, he experimented with conduction circuits similar to Morse's, varying battery power and the size of the galvanometer coil attached to the receiving needle, as well as the size of the submerged plates and the length of the conductors, to achieve greater distances. Lindsay eventually received a patent in 1854 for his method of telegraphing without wires and demonstrated it publicly across the Tay at Glencarse, a distance of three quarters of a mile.

In these early experiments, a young William Preece, recent graduate of King's College, London, and an employee of the Electric Telegraph Company, was Lindsay's assistant. In later years, Preece would become one of the more important persons in the development of wireless in Europe. As for Lindsay's dream of an electric telegraph to America, his calculations indicated it would require a battery 130 feet square, submerged plates 3000 feet square separated by a conducting wire roughly 2000 miles long, and a 200 pound coil at the receiving end (Fahie, 1899, 13-32).

He never built it.