a note, it is to be regretted, that the biographer* has allowed to remain without any comment; it being probable, from his known erudition, that he could have supplied the quotation of authority from Hooke's writings. It would also have been interesting to have ascertained, whether this memorandum was made by Dr. Robison before or after his having written the excellent account of the Steam Engine in the Encyclopedia Britannica. The project was either unknown to the Professor, at the period of publishing the article alluded to; or it was rejected on account of its questionable character. In the edition of that account, lately printed, no notice whatever is taken of Hooke's idea. The proposal has never presented itself to us in our perusal of the works of this most philosophical of modern mechanics.

No farther public attempt to raise water by steam (for hitherto, with one exception, this appears to have been the grand problem for solution,) was made until some years after the Marquis of Worcester's death; when, in 1682, we find Sir Samuel Moreland, at Paris, endeavouring to obtain the patronage of the French Government towards a scheme which he claims as his own, for raising water by the force of steam. In 1683 he exhibited his invention

* Edin. Encyclop. Memoir of Hooke by Brewster.

+ Robison's Mechanical Philosophy, 1823. A reprint of the various articles which were first published by Dr. Robison in the Encyclopædia Britannica. The notes to the article Steam Engine, in this collection, were written by the late venerable Mr. Watt of Soho.

to the French King at St. Germain's; but he ap pears to have been unsuccessful in his application to that Court for encouragement. No description of his apparatus, or of the principle or mode of its action, is known to be in existence. Fortunately, however, the results of some experiments made by Sir Samuel upon the elasticity of steam, are still preserved among the manuscripts in the British Museum.*

Sir Samuel's account is in the French language, written on vellum, in a very beautiful hand, and highly ornamented. The volume is stated on its title-page to have been presented to the King of France by Sir Samuel Moreland, Master of Mechanics to the King of England. It consists of twenty-two pages only, and purports to be an account of various machines for raising water. The part relating to the Steam Engine does not quite occupy four pages. Considering the period in which this portion of it was written, it is a very remarkable performance.

"Water being evaporated," says Sir Samuel, "by the force of fire, its vapour occupies a much larger space (about two thousand times) than it occupied before. And its power is so prodigious, as, if it were closely confined, to burst a cannon; but being governed upon statical principles, and by science reduced to measure, weight, and balance, it then bears itself quietly under the harness, (like good horses,) and becomes of great use to mankind, particularly for the raising of water, according to the following table, which shews the number of pounds

(French) weight which may be raised to the height of six inches eighteen hundred times a minute, in cylinders about half filled with water; as well as the different diameters and depths of the cylinders.

Sir Samuel's experiments must have been made with considerable care; and it is highly honourable to his mechanical accuracy that his estimate of the

rate of expansion of water, when converted into steam, should coincide with that which is given by an experienced engineer in the most recent book on the subject, as an approximation to be relied on in practice. Desaguliers long afterwards stated this expansion at 14,000 times! his estimate remaining unquestioned for more than half a century, is to be found in all books published prior to about 1800; when Professor Robison gave Mr. Watt's experiments, in which it was made between 18 and 1900 times the volume of water which produced it. The mode, too, of stating the quantity of water, which may be raised a certain height a given number of times in a minute, is still the modern method of estimating the power of Steam Engines. It is an obvious remark, that Sir Samuel must have been acquainted with the description in the "Century of Inventions," from quoting the Marquis of Worcester's improbable experiment as an illustration of the force of vapour. Lord Worcester had been dead several years before the date of Sir Samuel's exhibition of his apparatus; and whatever was its arrangement or principle, he is entitled to the merit of being the first accurate experimenter on the elastic force of steam.*

It has been remarked as a curious circumstance in the history of the Steam Engine, that almost every one who made an improvement, either in its con

* In the last edition of Ferguson's Mechanics, by Dr. Brewster, the expansion of steam is stated as it was given by Ferguson after Desaguliers, at 14,000 times; in no part of the excellent supplementary volume is there a correction made, or the true expansion stated—an error of moment, as the book has deservedly found its way into the hands of almost every mechanic.