Watt continued to pursue his studies as before. Though still occupied with his inquiries and experiments as to steam, he did not neglect his proper business, but was constantly on the look-out for improvements in instrument making. A machine which he invented for drawing in perspective proved a success; and he made a considerable number of them to order, for customers in London as well as abroad. He was also an indefatigable reader, and continued to extend his knowledge of chemistry and mechanics by perusal of the best books on these sciences. Above all other subjects, however, the improvement of the steam-engine continued to keep the fastest hold upon his mind. He still brooded over his experiments with the Newcomen model, but did not seem to make much way in introducing any practical improvement in its mode of working. His friend Robison says he struggled long to condense with sufficient rapidity without injection, trying one expedient after another, finding out what would do by what would _not_ do, and exhibiting many beautiful specimens of ingenuity and fertility of resource. He continued, to use his own words, “to grope in the dark, misled by many an _ignis fatuus_.” It was a favourite saying of his, that “Nature has a weak side, if we can only find it out;” and he went on groping and feeling for it, but as yet in vain. At length light burst upon him, and all at once the problem over which he had been brooding was solved. One Sunday afternoon, in the spring of 1765, he went to take an afternoon walk on the Green, then a quiet, grassy meadow, used as a bleaching and grazing-ground. On week-days the Glasgow lasses came thither with their largest kail-pots, to boil their clothes in; and sturdy queans might be seen, with coats kilted, tramping blankets in their tubs. On Sundays the place was comparatively deserted, and hence Watt, who lived close at hand, went there to take a quiet afternoon stroll. His thoughts were as usual running on the subject of his unsatisfactory experiments with the Newcomen engine, when the first idea of the separate condenser suddenly flashed upon his mind. But the notable discovery is best told in his own words, as related to Mr. Robert Hart, many years after:--