These experiments must have been made before the year 1663, in which the "Century of Inventions" was published. The description of the machine here given, like other descriptions in the same work, was only intended to express the effects produced, and the physical principle on which their production depends. It is, however, sufficiently explicit to enable any one conversant with the subsequent contrivance of Savery, to perceive that Lord Worcester must have contrived a machine containing all that part of Savery's engine in which the direct force of steam is employed. As in the above description, the separate boiler or generator of steam is distinctly mentioned; that the steam from this is conducted into another vessel containing the cold water to be raised; that this water is raised by the pressure of steam acting upon its surface; that when one vessel of water has thus been discharged, the steam acts upon the water contained in another vessel, while the first is being replenished; and that a continued upward current of water is maintained by causing the steam to act alternately upon two vessels, employing the interval to fill one while the water is discharged from the other.
On comparing this with the contrivance previously suggested by De Caus, it will be observed, that even if De Caus knew the physical agent by which the water was driven upwards in the apparatus contrived by him, still it was only a means of causing a vessel of boiling water to empty itself; and before a repetition of the process could be obtained, 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 and 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.
(28.) It appears, by a MS. in the Harleian Collection in the British Museum, that a mode of applying steam to raise water was proposed to Louis XIV. by Sir Samuel Morland. It contains, however, nothing more than might have been collected from Lord Worcester's description, and is only curious, because of the knowledge the writer appears to have had of the expansion which water undergoes in passing into steam. The following is extracted from the MS.: