Allen, John, his power-driven boat referred to. 38-39.

Beighton, Henry, probable relations with Triewald, x.

Boyle, Robert, referred to, 21.

Calley, John, assists Newcomen in his invention, 2-4.

Calley, Samuel (son of the preceding), assists Ridley and Triewald at Newcastle, 6, 8, 53.

Carlscrona docks, 39-42.

Condensing water, effect of injecting into cylinder revealed by accident, ix-x, 2-3.

Dannemora fire-machine, description of, 9-14; dimensions, xi-xii, 25; its power, 25-28, 33-35, 41-42; was not successful, ix .

Dannemora mines, capacity of horse whims at, 33-34; cost, 4, 8, 53.

Fire-machines, erected by 1717 in England, 5, 53; erected outside Great Britain, 39, 54.

Fire-protection in London, 37.

Guericke, Otto von, referred to, 15n.

Halley, Edmund, referred to, 20.

Injection of condensing water into cylinder, effect revealed accidentally, ix-x, 2-3.

Königsberg, Hungary, fire-machine at, 29-32; dimensions, 30; compared with horse whims, 31; compared with the Dannemora machine, 32-33.

Leopold, gunpowder at Vienna, referred to, 29, 31.

Liége, fire-machine at, referred to, 39.

London, fire-machine [York Buildings engine] used for supplying houses with water, 36-38, 43, 45, 54; its dimensions, 37-38.

Meijer, Gerhard, referred to, 29, 54.

Newcastle-on-Tyne, fire-machine at, 5-8; Triewald assists in its erection, 6-8.

Newcomen, Thomas, invents his fire-machine, 2-3; his close acquaintance with the mining industry explained, ix, 2; the effect of injecting the condensed water into the cylinder accidentally revealed to him, ix-x, 2-3; his fire-machine not patented, 3; forms a company with Calley and Savery, ix, 3; erects his first engine, 4, 53; its dimensions, 4; news of the engine spreads rapidly, 4-5; secrets of its construction jealously guarded, 5; his theoretical knowledge criticised by Triewald, 7.

Newton, Sir Isaac, referred to, 7, 53.

Patents for inventions, reference to English system, 4n.

Potter, Isaac, and the Königsberg fire-machine, 31-32, 5-8; obtains the assistance of Triewald, 6.

Savery, Thomas, his patent and a subsidy, 1, 53.

Triewald, Mårten, eulogy by H. Kolthoff, xix, 53; his probable relations with Henry Beighton, x; his friendship with Ridley, 6; assists Ridley in the erection of the Newcastle engine, 6-8; criticises the theoretical knowledge of Newcomen, 7; forms a company with Samuel Calley, 8; states that he made improvements in the fire-machine, x, xi, 9; list of his writings, 55-59.

Vienna fire-machine, referred to, 39, 46.

Water supply in London, 36.

Weidler, Friedrich, quoted, 38.

Worster, Benjamin, referred to, 21.