HIGH-PRESSURE STEAM As regards the use of steam under high pressure, somewhat the same remarks apply, so far as concerns the conservatism of mankind, and the influence which a great mind exerts upon its generation. Just why Watt should have conceived an antagonism to the idea of high-pressure steam is not altogether clear. It has been suggested, indeed, that this might have been due to the fact that a predecessor of Watt had invented a high-pressure engine which did not use the principle of condensation, but exhausted the steam into open space. As early as 1725, indeed, Leupold in his _Theatrum Machinarum_, had described such a non-condensing engine, which, had it been made practically useful, would have required a high pressure of steam. Partly through the influence of this work, perhaps, there came to be an association between the words high pressure and non-condensing, so that these terms are considered to be virtually synonymous; and since Watt's great contribution consisted of an application of the idea of condensation, he was perhaps rendered antagonistic to the idea of high pressure, through this psychological suggestion. In any event, the antagonism unquestionably existed in his mind; though it has often enough been pointed out that this seems the more curious since high-pressure steam would so much better have facilitated the application of that other famous idea of Watt, the use of the expansive property of steam. Curiously enough, however, the influence of Watt led to experiments in high-pressure steam through an indirect channel. The contemporary inventor, Trevithick, in connection with his partner, Bull, had made direct-acting pumping engines with an inverted cylinder, fixed in line with the pump rod, and actually dispensing with the beam. But as these engines used a jet of cold water in the exhaust pipe to condense the steam, Boulton and Watt brought suit successfully for infringement of their patent, and thus prevented Trevithick from experimenting further in that direction. He was obliged, therefore, to turn his attention to a different method, and probably, in part at least, in this way was led to introduce the non-condensing, relatively high-pressure engine. This was used about the year 1800. At the same time somewhat similar experiments were made by Oliver Evans in America.