A study of the problem was made upon Boulton's return and he agreed to close two departments of the business which were so far unprofitable, thus entering upon the right path. The engine having proved itself indispensable, the demand for it was becoming great and pressing from various countries. To concentrate upon its manufacture was obviously the true policy. The great captain's enterprise was not often expended upon failures, and it is with pleasure we find that among the profitable branches which Boulton had encouraged Watt in introducing at Soho, was the copying-press, which Watt invented in 1778, and which we use to this day. In July of that year he writes Dr. Black that he has "lately discovered a method of copying writing instantaneously, provided it has been written within twenty-four hours. I send you a specimen and will impart the secret if it will be of any use to you. It enables me to copy all my business letters." He kept this secret for two years, and in May, 1780, secured a patent after he had completed details of the press and experimented with the ink. One hundred and fifty were made and sold. Thirty of these went abroad. It steadily made its way. Watt, writing some thirty years later, said it had proved so useful to him that it was well worth all the trouble of perfecting it, even if it brought no profit. We think of Watt and the steam engine appears. Let us however note the unobtrusive little copying-press on the table at his side. Extremes meet here. It would be difficult to name an invention more universally used, in all offices where man labors in any field of activity. In the list of modest inventions of greatest usefulness, the modern copying-press must take high rank, and this we owe entirely to Watt. Of the same period as the copying-machine is his invention of a drying-machine for cloth, consisting of three cylinders of copper over which the cloth must turn over and under while cylinders are filled with steam, the cloth to be alternately wound off and on the two wooden rollers, by which means it will pass over three cylinders in succession. This machine was erected for Watt's father-in-law, Mr. MacGregor in Glasgow, by an ingenious mechanic, John Gardiner, often employed by Watt in earlier years. "This I apprehend," he writes to David Brewster in 1814, "to be the original from which such machines were made." When we consider the extent to which such steam drying-machines are used in our day, our estimate of the credit due to Watt cannot be small. The drying-machine is no unfit companion to the copying-machine.