Although, in the treatise referred to, Savery describes an engine with two furnaces, the drawing which he presented to the Royal Society showed only one; and it appears that in another of his designs he showed only one cylindrical vessel instead of two. In order to exhibit the working of his engine on a larger scale than in the model, he proceeded to erect one in a potter’s house at Lambeth, where, Switzer says, though it was a small engine, the water struck up the tiles and forced its way through the roof in a manner that surprised all the spectators. Switzer mentions other engines erected after Savery’s designs for the raising of water at Camden House and Sion House, which proved quite successful. The former, he says, was the plainest and best proportioned engine he had seen: it had only a single condensing vessel; and “though but a small one in comparison with many others of the kind that are made for coal-works, it is sufficient for any reasonable family, and other uses required for it in watering middling gardens.”[33] Four receivers full of water, or equal to 52 gallons, were raised every minute, or 3110 gallons in the hour; whilst, in the case of the larger engines with double receivers, 6240 gallons an hour might easily be raised. The cost of the smaller engine was about fifty pounds, and the consumption of coal about a bushel in the twenty-four hours, supposing it was kept constantly at work during that time. [33] Switzer, ‘Introduction to a General System of Hydrostaticks and Hydraulicks,’ 237. [Illustration: HUEL VOR, WITH REMAINS OF THE OLD WORKS. [By R. P. Leitch.]]