chapter 8._

ELECTRICITY: A. D. 1854-1866. The Atlantic Cable.

"Cyrus Field ... established a company in America (in 1854), which ... obtained the right of landing cables in Newfoundland for fifty years. Soundings were made in 1856 between Ireland and Newfoundland, showing a maximum depth of 4,400 metres. Having succeeded after several attempts in laying a cable between Nova Scotia and Newfoundland, Field founded the Atlantic Telegraph Company in England. ... The length of the ... cable [used] was 4,000 kilometres, and was carried by the two ships Agamemnon and Niagara. The distance between the two stations on the coasts was 2,640 kilometres. The laying of the cable commenced on the 7th of August, 1857, at Valentia (Ireland); on the third day the cable broke at a depth of 3,660 metres, and the expedition had to return. A second expedition was sent in 1858; the two ships met each other half-way, the ends of the cable were joined, and the lowering of it commenced in both directions; 149 kilometres were thus lowered, when a fault in the cable was discovered. It had, therefore, to be brought on board again, and was broken during the process. After it had been repaired, and when 476 kilometres had been already laid, another fault was discovered, which caused another breakage; this time it was impossible to repair it, and the expedition was again unsuccessful, and had to return. In spite of the repeated failures, two ships were again sent out in the same year, and this time one end of the cable was landed in Ireland, and the other at Newfoundland. The length of the sunk cable was 3,745 kilometres. Field's first telegram was sent on the 7th of August, from America to Ireland. The insulation of the cable, however, became more defective every day, and failed altogether on the 1st of September. From the experience obtained, it was concluded that it was possible to lay a trans-Atlantic cable, and the company, after consulting a number of professional men, again set to work. ... The Great Eastern was employed in laying this cable. This ship, which is 211 metres long, 25 metres broad, and 16 metres in height, carried a crew of 500 men, of which 120 were electricians and engineers, 179 mechanics and stokers, and 115 sailors. The management of all affairs relating to the laying of the cable was entrusted to Canning. The coast cable was laid on the 21st of July, and the end of it was connected with the Atlantic cable on the 23rd. After 1,326 kilometres had been laid, a fault was discovered, an iron wire was found stuck right across the cable, and Canning considered the mischief to have been done with a malevolent purpose. On the 2nd of August, 2,196 kilometres of cable were sunk, when another fault was discovered. While the cable was being repaired it broke, and attempts to recover it at the time were all unsuccessful; in consequence of this the Great Eastern had to return without having completed the task. A new company, the Anglo-American Telegraph Company, was formed in 1866, and at once entrusted Messrs. Glass, Elliott and Company with the construction of a new cable of 3,000 kilometres. Different arrangements were made for the outer envelope of the cable, and the Great Eastern was once more equipped to give effect to the experiments which had just been made. The new expedition was not only to lay a new cable, but also to take up the end of the old one, and join it to a new piece, and thus obtain a second telegraph line. The sinking again commenced in Ireland on the 13th of July, 1866, and it was finished on the 27th. On the 4th of August, 1866, the Trans-Atlantic Telegraph Line was declared open."

_A. R. von Urbanitzky, Electricity in the Service of Man, pages 767-768._

ELECTRICITY: A. D. 1876-1892. The Telephone.

"The first and simplest of all magnetic telephones is the Bell Telephone." In "the first form of this instrument, constructed by Professor Graham Bell, in 1876 ... a harp of steel rods was attached to the poles of a permanent magnet. ... When we sing into a piano, certain of the strings of the instrument are set in vibration sympathetically by the action of the voice with different degrees of amplitude, and a sound, which is an approximation to the vowel uttered, is produced from the piano. Theory shows that, had the piano a much larger number of strings to the octave, the vowel sounds would be perfectly reproduced. It was upon this principle that Bell constructed his first telephone. The expense of constructing such an apparatus, however, deterred Bell from making the attempt, and he sought to simplify the apparatus before proceeding further in this direction. After many experiments with more, or less unsatisfactory results, he constructed the instrument ... which he exhibited at Philadelphia in 1876. In this apparatus, the transmitter was formed by an electro-magnet, through which a current flowed, and a membrane, made of gold-beater's skin, on which was placed as a sort of armature, a piece of soft iron, which thus vibrated in front of the electro-magnet when the membrane was thrown into sonorous vibration. {777} ... It is quite clear that when we speak into a Bell transmitter only a small fraction of the energy of the sonorous vibrations of the voice can be converted into electric currents, and that these currents must be extremely weak. Edison applied himself to discover some means by which he could increase the strength of these currents. Elisha Gray had proposed to use the variation of resistance of a fine platinum wire attached to a diaphragm dipping into water, and hoped that the variation of extent of surface in contact would so vary the strength of current as to reproduce sonorous vibrations; but there is no record of this experiment having been tried. Edison proposed to utilise the fact that the resistance of carbon varied under pressure. He had independently discovered this peculiarity of carbon, but it had been previously described by Du Moncel. ... The first carbon transmitter was constructed in 1878 by Edison."

_W. H. Preece, and J. Maier, The Telephone,