VIII. On the progressive improvements made in the efficiency of steam engines in Cornwall, with investigations of the methods best adapted for imparting great angular velocities

In the year 1827, some observations I had made on steam engines were honoured by a place in the Philosophical Transactions. I am therefore induced to lay before the Society further particulars illustrative of the progress by which that most important machine has reached its actual high state of improvement. On a subject of less magnitude I should not have presented to the Society a mere collection of matter in detail, unconnected by any general arrangement of the facts: but every thing appears to me of great interest that bears on the history of an invention that has continually advanced towards perfection by the aid of chemical, mechanical, and mathematical sciences; an invention that has already altered and improved the condition of mankind; and seems destined to produce consequences the most beneficial to civilized society, by extending the dominion of intellect over muscular power and brute force. I am moreover desirous of preserving information derived from documents which have never yet passed out of private hands, and are consequently liable to be lost or destroyed. For all practical purposes the steam engine must be considered as originating with Mr. Newcomen; the introduction of a moveable diaphragm between the active power and the vacuum or less elastic medium, being essential to the very principle of the machine as a moving power.