[88] The telescope was mounted with two parallel horizontal hairs in the focus of the eyeglass, crossed by one perpendicular hair. The measuring pole was divided into feet and inches, so that, wrote Watt, “if the hairs comprehend one foot at one chain distance, they will comprehend ten feet at ten chains,” and so on. This invention Watt made in 1770, and used the telescope in his various surveys. Eight years later, in 1778, the Society of Arts awarded to a Mr. Green a premium for precisely the same invention.
[89] Letter to Small, 24th Nov. 1772. Watt, however, took no steps to bring this invention before the public, and in 1777, a similar instrument having been invented by Dr. Maskelyne, was presented by him to the Royal Society. Thus Watt also lost the credit of this invention.
Such were the multifarious pursuits in which this indefatigable student and inquirer was engaged; all tending to cultivate his mind and advance his education, but comparatively unproductive, so far as regarded pecuniary return. So unfortunate, indeed, had Watt’s speculations proved, that his friend Dr. Hutton, of Edinburgh, addressed to him a New-year’s day letter, with the object of dissuading him from proceeding further with his unprofitable brain-distressing work. “A happy new year to you!” said Hutton; “may it be fertile to you in lucky events, but no new inventions!” He went on to say that invention was only for those who live by the public, and those who from pride choose to leave a legacy to the public. It was not a thing likely to be well paid for under a system where the rule was to be the best paid for the work that was easiest done. It was of no use, however, telling Watt that he must not invent. One might as well have told Burns that he was not to sing because it would not pay, or Wilkie that he was not to paint, or Hutton himself that he was not to think and speculate as to the hidden operations of nature. To invent was the natural and habitual operation of Watt’s intellect, and he could not restrain it.
Watt had already been too long occupied with this profitless work: his money was all gone; he was in debt; and it behoved him to turn to some other employment by which he might provide for the indispensable wants of his family. Having now given up the instrument-making business, he confined himself almost entirely to surveying. Among his earliest surveys was one of a coal canal from Monkland to Glasgow, in 1769; and the Act authorising its construction was obtained in the following year. Watt was invited to superintend the execution of the works, and he had accordingly to elect whether he would go on with the engine experiments, the event of which was doubtful, or embrace an honourable and perhaps profitable employment, attended with much less risk and uncertainty. His necessities decided him. “I had,” he said, “a wife and children, and saw myself growing grey without having any settled way of providing for them.” He accordingly accepted the appointment offered him by the directors of the canal, and undertook to superintend the construction of the works at a salary of 200_l._ a year. At the same time he determined not to drop the engine, but to proceed with it at such leisure moments as he could command.