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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. By Davies Gilbert, Esq. President. 
Read March 4, 1830. 
In the year 1827, some observations I had made on steam engines were ho- 
noured 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 improve- 
ment. On a subject of less magnitude 1 should not have presented to the 
Society a mere collection of matter in detail, unconnected by any general ar- 
rangement 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 docu- 
ments 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 origina- 
ting 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. 
Mr. Newcomen’s engines were brought into Cornwall very early in the last 
century, where they immediately superseded the laborious method of drawing 
water by human exertions, applied through the simple medium of a chain 
pump, similar in construction to those at present used on board large ships. 
So inartificial, indeed, was the machinery in mines at this comparatively recent 
MDCCCXXX. R 
