If, having comprehended the apparatus here described, the reader refers to the description of the Marquis of Worcester's machine, he will find that all the conditions therein laid down are fulfilled by it. One vessel (E) of "water rarefied by fire" may by such means "drive up forty (or more) of cold water; and the man that tends the work has but to turn two cocks, that one vessel (V) of water being consumed, another (V′) begins to force and refill with cold water, and so on successively, the fire being tended and kept constant; which the self-same person may likewise abundantly perform, in the interim between the necessity of turning the said cocks." On comparing this with the contrivance previously suggested by De Caus, it will be observed, that even if De Caus [Pg034] knew the physical agent by which the water was driven upwards in the apparatus described by him, still it was only a method of causing a vessel of boiling water to empty itself; and before a repetition of the process could be made, the vessel should be refilled, and again boiled. In the contrivance of Lord Worcester, on the other hand, the agency of the steam was employed in the same manner as it is in the steam engines of the present day, being generated in one vessel, and used for mechanical purposes in another. Nor must this distinction be regarded as trifling or insignificant, because on it depends the whole practicability of using steam as a mechanical agent. Had its action been confined to the vessel in which it was produced, it never could have been employed for any useful purpose. Although many of the projects contained in Lord Worcester's work were in the highest degree extravagant and absurd, yet the engine above described is far from being the only practicable and useful invention proposed in it. On the contrary, many of his inventions have been reproduced, and some brought into general use since his time. Among these may be mentioned, stenography, telegraphs, floating baths, speaking statues, carriages from which horses can be disengaged if unruly, combination locks, secret escutcheons for locks, candle moulds, the rasping mill, the gravel engine, &c. SIR SAMUEL MORLAND, 1683. (18.) Sir Samuel Morland was the son of a baronet of the same name, who had received his title at the restoration for some services to the royalist party, performed by him during the wars of the Commonwealth. He appears to have devoted much attention to mechanics, in which he attained some celebrity. He was the reputed inventor of several ingenious contrivances, such as the drum capstan for ships, the plunger pump, &c. He also investigated various questions in acoustics, and among others, the determination of the best form for the speaking-trumpet.