In a former part of this work, we gave a list of the principal Tin and Copper Mines in this county; but as we apprehended the limits of it would not allow a particular description of them, we have since, at the suggestion of some of our subscribers, curtailed the historical and topographical notices, with the view to enable us to present our readers with some little particulars as to the situation and nature of the most valuable mines now working. In passing through the county according to the plan of our several Excursions, there are not any mines deserving of particular attention, until the traveller arrives at St. Austell; here it is necessary that he should make some stay, as the vicinity of the town possesses many attractions, and the numerous works now in progress will amply gratify his curiosity. The most considerable _Tin Mine_ in the county is _Polgooth_, which is situated about two miles south-west of St. Austell; and even in Borlase’s time, is said to have yielded to its proprietors a profit of £20,000 annually for some years. Owing, however, to some unfortunate disputes, the operations have been suspended for nearly 20 years, but have lately been resumed with increased vigour. From the extensive nature of the works carried on in this mine, the whole surface of the country in its vicinity, has been completely disfigured, and presents a very gloomy aspect. The quantity of ore which has been raised from this mine, during the progress of its workings, is far beyond calculation: the immense piles of earth, which have been excavated and thrown up, have quite a mountainous appearance: roads have been formed in several directions leading to the places or shafts, where the miners are at work; and the dreariness of the scene is only enlivened by the humble cottages, which have been erected for their residence. The number of shafts which have been sunk in this mine, amount to near 50, and the greater part of them are mostly working; but since the introduction of steam engines, the operations have been considerably increased, as the water is now raised to the level of the adits, and which before had in some cases overflowed certain parts of the mine. The introduction of steam engines for drawing off the water from the mines in Cornwall, is one of the most valuable discoveries imaginable; and the greatest advantages have attended these powerful machines, while on the other hand few accidents have been occasioned by their adoption.[48] In Dr. Maton’s Observations on the Western Counties, is the following description of a _Steam Engine_; but since that time, their powers of acting have been considerably augmented; and on some occasions they are now made on a very large scale, with _cylinders_ even 90 inches in diameter.