After the publication of the work by Brancas, more than thirty years elapsed ere the publication of the Marquis's "Century" recalled the attention of the scientific world to this important subject; and this invention, which he states as having been completely carried into effect, was evidently very different from that of his predecessors. It is said that the Marquis, while confined in the Tower of London, was preparing some food in his apartment, and the cover of the vessel, having been closely fitted, was, by the expansion of the steam, suddenly forced off and driven up the chimney. This circumstance attracting his attention, led him to a train of thought, which terminated in the completion of his "water-commanding engine."[9] Of the Marquis's invention no record has been preserved beyond the articles to which we have already alluded in the present work: and in the absence of other data, the Editor readily introduces Professor Millington's design for an engine on similar principles; and which, with a few alterations, might be made available for the purposes recommended by our author. [9] _Vide_ Historical and Descriptive Account of the Steam-engine, by C. F. Partington, p. 6. [Illustration] In this diagram, _q_ represents a strong and close vessel or boiler to contain water, set in brick work like a common copper, with a fire-place _r_ underneath it, having a chimney _s_. The boiler thus constructed, is intended to afford the means of producing steam: and if we conceive two casks or strong hollow vessels of any form to be placed under the surface of the water, near the boiler, as at _t_ and _v_, and that each of these vessels has a valve opening into it in its lower part as _u_ _u_, and two pipes _w_ _w_, proceeding from the upper part of the vessels to the top of the steam boiler _q_, while two other pipes _x_ _x_ proceed from the lower parts of these vessels into a cistern _y_, forty feet above the level of the water; an apparatus thus constructed will nearly form the water-commanding engine, for if the vessels _t_ and _v_ are both filled with water by the valves _u_ _u_, and the cock _z_ be opened after the steam has accumulated in the boiler, the elastic fluid thus generated will instantly rush down into the vessel _t_, and when the surface of the water is heated expel the whole of its contents up the pipe _a x_, into the cistern _y_, where it will be retained by a valve opening upwards in any part of that pipe, as at _a_. This done, the cock _z_ must be shut, and after permitting the steam to accumulate for a short time, that at _b_ must be opened, and the steam will rush into the vessel _v_ and perform a similar office, _c_ being the valve to prevent the return of the water. When the steam is shut off from the vessel _t_, the elastic fluid which had previously been introduced to expel the water, will be condensed by the cold media round it, and thus a vacuum will be produced in the vessel _t_, consequently