As to the lethargy from which Roebuck sought to raise Watt, it was merely the temporary reaction of a mind strained and wearied with long-continued application to a single subject, and from which it seemed to be occasionally on the point of breaking down altogether. To his intimate friends, Watt bemoaned his many failures, his low spirits, his bad health, and his sleepless nights. He wrote to his friend Dr. Small[83] in January, 1769, “I have many things I could talk to you about--much contrived, and little executed. How much would good health and spirits be worth to me!” A month later he wrote, “I am still plagued with headaches, and sometimes heart-aches.”
[83] Dr. Small was born in 1734 at Carmylie, Angus, Scotland, of which parish his father was the minister. He had been for some time the professor of Natural Philosophy in the University of Williamsburg, Virginia, from whence he returned to England and settled at Birmingham.
It is nevertheless a remarkable proof of Watt’s indefatigable perseverance in his favourite pursuit, that at this very time, when apparently sunk in the depths of gloom, he learnt German for the purpose of getting at the contents of a curious book, the _Theatrum Machinarum_ of Leupold, which just then fell into his hands, and contained an account of the machines, furnaces, methods of working, profits, &c., of the mines in the Upper Hartz. His instructor in the language was a Swiss dyer,[84] settled in Glasgow. With the like object of gaining access to untranslated books in French and Italian--then the great depositories of mechanical and engineering knowledge--Watt had already mastered both those languages.
[84] “I have,” he writes, “just now got a curious book, being an account of all the machines, furnaces, methods of working, profits, &c., of the mines of the Upper Hartz. It is unluckily in German, which I understand little of, but am improving in by the help of a truly Chymical Swiss Dyer, who is come here to dye standing red on linen and cotton, in which he is successful. He is according to the custom of philosophers ennuyé to a great degree, but seems to be more modest than is usual with them; and, what is still more unusual, is attached only to his dyeing, though he has a tolerable knowledge of chymestry. He promises to make me a coat that will not wet though boiled in water. This would be of great use to a hundred people I see just now running by, wet to the skin.... I verily believe the drops are an inch in diameter! To return to the book--it contains an account of all the unsuccessful experiments that have been tried in the Hartz, and I assure you it gives me some consolation to see the great Liebnitz, the rival of Newton, bungling repeatedly, applying wind mills to raise ore while water ran idle past him. There is among other machines the fellow of Blackie’s, only worked by water, and a full and true account of why it did not succeed, which he should read. Their machines in general display great ingenuity though ignorance of principles.”--Watt to Small, May 28, 1769. Boulton MSS.