caused the neighbouring Dolcoath in 1811 to give Trevithick's plans free scope. The long smouldering rivalry between low and high pressure, on the eve of the final discomfiture of the former, burst forth in loud words and evil prognostications, causing the mining interest of Cornwall to appoint an examiner who should publish monthly the duty performed by the various pumping engines, the first of which appeared in the autumn of 1811, when Trevithick was building his boilers in Dolcoath, and preparing the engines, as far as was possible, to submit to strong steam. By expansive valves and suitable gear, balance of power between the engine and the pump-work necessitating balance-bobs, strengthening the pit-work to bear the more powerful and sudden movement, and fifty other things, which we know must have presented themselves in such work, occupied the greater part of Trevithick's time from 1811 to 1814. That first report enumerates twelve pumping-engines, probably all of them Watt engines, averaging a duty of seventeen millions. [Footnote 118: See Lean's Historical Statement, p. 154; published 1839.] [Footnote 119: See vol. i., p. 7.] We have before traced the rapid and immense increase in the power and in the duty of Cornish pumping engines from 1811, and it may be taken as comparatively true in the larger sense applying to the improvement of the steam-engine everywhere. Dolcoath Mine, one hundred years ago, under the management of Trevithick, sen., followed by his son as the strong-steam engineer, and by his grandson as one of the committee of management in these modern times, has served during that long period to illustrate the progress of the steam-engine, and still in active operation, was thus spoken of in 'The Times' of Dec. 18th, 1871:--"This old and extraordinary mine is now raising about 100 tons of tin every month, worth from 8000_l._ to 9000_l._" CHAPTER XXI. ENGINES FOR SOUTH AMERICA. [Rough draft.] "SIR, "CAMBORNE, _May 20th, 1813_.