All About Engines

46 All About Engines perature and pressure are now lower; the steam has lost some heat, and that heat has been turned into useful work in pushing the piston. All engines, from the time of Watt, are worked expansively, whether they are condensing or non-condensing. The disadvantage of the latter is that the steam which is discharged into the air is still capable of doing work, and therefore some of the heat which it has taken up from the fire is being wasted. As we shall return again to questions of the power and efficiency of steam engines, we can now follow the career of James Watt a little farther. When he entered into partnership with Boulton his troubles were by no means over. His patent had been in existence for some years, there were un- scrupulous rivals in the field, preliminary expenses would be heavy, and they felt that unless they could obtain an extension of time their efforts might bring them no benefit. Two courses were open to them : to secure an extension of the patent by applying to the Patent Office, or to get an Act of Parliament passed protecting them for a term of years. They chose the latter, and after a great deal of trouble and delay, Parliament, in 1775, granted them an extension of twenty-five years. The first engine was constructed to blow the bellows of John Wilkinson’s iron works at Broseley, in 1776, and in the same year another was supplied to a distillery at Stratford. Then the Cornish mines claimed attention. They were so far from the coal- fields, and the consumption of coal by Newcomen’s