subject, and in lecturing on it in Dundee, Glasgow, and other places since 1831. Recently he had made additional experiments, and succeeded in crossing the Tay where it was three-quarters of a mile broad. His method had always been to immerse two plates or sheets of metal on the one side, and connect them by a wire passing through a coil to move a needle, and to have on the other side two sheets similarly connected, and nearly opposite the two former. Experiments had shown that only a fractional part of the electricity generated goes across, and that the quantity that thus goes across can be increased in four ways: (1) by an increased battery power; (2) by increasing the surface of the immersed sheets; (3) by increasing the coil that moves the receiving needle; and (4) by increasing the lateral distance of the sheets. In cases where lateral distance could be got he recommended increasing it, as then a smaller battery power would suffice. In telegraphing by this method to Ireland or France abundance of lateral distance could be got, but for America the lateral distance in Britain was much less than the distance across. In the greater part of his experiments the distance at the sides had been double the distance across; but in those on the Tay the lateral distance was the smaller, being only half a mile, while the distance across was three-quarters of a mile.

"Of the four elements above mentioned, he thought that if any one were doubled the portion of electricity that crossed would also be doubled, and if all the elements were doubled the quantity transmitted would be eight times as great. In the experiments across the Tay the battery was of 4 square feet of zinc, the immersed sheets contained about 90 square feet of metal, the weight of the copper coil was about 6 lb., and the lateral distance was, as just stated, less than the transverse; but if it had been

a mile, and the distance across also a mile, the signals would, no doubt, have been equally distinct. Should this law (when the lateral distance is equal to the transverse) be found correct, the following table might then be formed:

"But supposing the lateral distance to be only half the transverse, then the space crossed might be 16,000 miles; and if it was only a fourth, then there would be 8000 miles a much greater distance than the breadth of the Atlantic. Further experiments were, however, necessary to determine this law, but, according to his calculations, he thought that a battery of 130 square feet, immersed sheets of 3000 square feet, and a coil of 200 lb.,1 would be sufficient to cross the Atlantic with the lateral distance that could be obtained in Great Britain."

After the reading of the paper Lindsay carried out some very successful experiments across the river Dee, in the

1 My readers will smile at the suggestion of such galvanometer coils, but they should remember that forty years ago matters electrical were largely ordered by the rule of thumb. The electro-magnet first used by Morse on the Washington-Baltimore line (1844), and exhibited in Europe, weighed 185 lb. The arms were 3 inches long and 18 inches diameter, the wire (copper) being that known as No. 16-the same size as the line wire, it being then supposed that the wire of the coils and of the line should be of the same size throughout. Down to 1860 not a few practical telegraphists held this view. See D. G. FitzGerald in the London 'Electrical Review,' August 9, 1895, p. 157.

presence of Lord Rosse, Prof. Jacobi of St Petersburg, and other members of the Association. In February 1860 he made Liverpool the scene of his operations, but there, strange to say, he had not the success which hitherto attended him. The experiments failed, being "counteracted by some unaccountable influence which he had not before met with." However, in the following July he was again successful at Dundee in his experiments across the Tay, below the Earn, where the river is more than a mile wide. In communicating these results to the 'Dundee Advertiser' (July 10, 1860), he says: "The experiment was successful, and the needle was strongly moved; but as I had no person with me capable of sending or reading a message, it [regular telegraphic signalling] was not attempted."

This was Lindsay's last public connection with the telegraph, but to the end of his life (June 29, 1862) he remained perfectly convinced of the soundness of his views and of their ultimate success. 1

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1 On the eve of the centenary of Lindsay's birth the 'Dundee Advertiser' (September 7, 1899) published a very appreciative sketch of "the famous Scottish inventor," which is largely based on my articles quoted on p. 14, supra. As a result we are gratified to learn that a bust of James Bowman Lindsay, a pioneer of wireless telegraphy by the conductive method, is to be placed in the Victoria Art Galleries of Dundee. The bust is to be of white Carrara marble, and will be the gift of Lord Provost M'Grady, Mr George Webster of Edinburgh being the sculptor. It has further been proposed to erect a monument over Lindsay's grave hy public subscription.”— 'Electrician,' vol. xliii. p. 795.

J. W. WILKINS-1845.

In the New York Electrical Engineer' of May 29, 1895, it was claimed for Prof. Trowbridge (of whom we shall have more to say later on) that he was the first to telegraph without wires in 1880.

The paragraph in which this claim, unfounded as we already see, was advanced, besides drawing renewed attention to Prof. Trowbridge's experiments, had the merit of calling forth an interesting communication from our own Mr J. W. Wilkins, one of the very few telegraph officers of Cooke & Wheatstone's days still with us, and whose early and interesting reminiscences I hope we may yet see.1

Writing in 'The Electrician,' July 19, 1895, Mr Wilkins says:

"Nearly fifty years ago, and thirty years before Prof. Trowbridge made original researches between the Observatory at Cambridge and the City of Boston,' the writer of these lines had also researched on the same subject, and a year or two later published the results of his investigations in an English periodical-the 'Mining Journal' of March 31, 1849-under the heading 'Telegraph communication between England and France.' In that letter, after going into the subject very much like the American Professor in 1880, there will be found my explanation-also not differing much from the Professor's- -as to how the thing was to be done; except that, in my case, I proposed a new and delicate form of galvanometer or telegraph instrument for the purpose, while he made use of the well-known telephone. I suggested the erection of lengths of telegraph wires on the

1 Mr Wilkins is the author of two English patents: (1) Improvements in Electric Telegraphs, January 13, 1853; and (2) Improvements in obtaining power by Electro-Magnetism, October 28, 1853.

English and French coasts, with terminals dipping into the earth or sea, and as nearly parallel as possible to one another; and I suggested a form of telegraph instrument consisting of 'coils of finest wire, of best conductibility,' with magnets to deflect them on the passage of a current of electricity through them, which I expected would take place on the discharge of electricity through the circuits on either side of the water; anticipating, of course, that a portion of the current would flow from the one pair of earth-plates-terminals of one circuit to the other pair of terminals on the opposite shore.

"It may be interesting to relate how I came to think that telegraphy without wires was a possibility, and that it should have appeared to me to have some value, at a time when gutta-percha as an insulator was not imagined, or the ghost of a proposition for a submarine wire existed. At that time, too, it was with the utmost difficulty that efficient insulation could be maintained in elevated wires if they happened to be subject to a damp atmosphere.

"It was in the year 1845, and while engaged on the only long line of telegraph then existing in EnglandLondon to Gosport that my observations led me to question the accepted theory that currents of electricity, discharged into the earth at each end of a line of telegraph, sped in a direct course-instinctively, so to say-through the intervening mass of ground to meet a current or find a corresponding earth-plate at the other end of it to complete the circuit. I could only bring myself to think that the earth acted as a reservoir or condenser-in fact, receiving and distributing electricity almost superficially for some certain or uncertain distance around the terminal earths, and that according to circumstances only. A year later, while occupied with the installation of telegraphs for Messrs Cooke & Wheatstone (afterwards the Electric Tele