At this period, the limit of time assigned by professional men for the exhaustion of coal-mines was far distant and there was no dread of scarcity. There were still extensive mines to be worked in the two Americas. The manu-factories, appropriated to so many different uses, locomotives, steamers, gas works, &c., were not likely to fail for want of the mineral fuel; but the consumption had so increased during the last few years, that certain beds had been exhausted even to their smallest veins. Now deserted, these mines perforated the ground with their useless shafts and forsaken galleries. This was exactly the case with the pits of Aberfoyle.