from the mingling of steam with the air in the vessel, or whether he was conscious of the great expansion of steam and the increase from pressure. In one of his descriptions, he uses the following terms of explanation :-" The violence of the vapour which causes the water to rise proceeds from the same water, which vapour goes out from the cock after the water with great violence." From this passage, which at the best is most remarkable for its obscurity, M. Arago deduces that Solomon de Caus understood the property of elasticity to belong to steam, irrespective of the air with which it is mixed. For many centuries, the expansive power of air, when acted upon by heat, had been known. This fact, we believe, is admitted by all authors; and to us it seems probable that the elasticity of steam was also discovered, and that Hero himself was acquainted with the property.

The first of a long catalogue of inventors presented by England is Edward Somerset, marquis of Worcester. This nobleman having engaged himself with the royalist forces in the parliamentary wars, was taken prisoner and confined in Ireland, from which place he made his escape, and joined the king, Charles II., in France. Venturing again into England on a secret embassy, he was seized in London and committed to the Tower, from which he was not released till the restoration of the monarchy. In 1663, he published a work called "A century of the names and scantlings of such

inventions as at present I can call to mind to have tried and perfected, which (my former notes being lost) I have, at the instance of a powerful friend, endeavoured, now in the year 1655, to set down in such a way as may sufficiently instruct me to put any of them in practice." In this book there are many extravagant propositions, but there are also many useful inventions, which have been adopted and valued in our own times, not, however, from Worcester's descriptions, for they are so vague and unsatisfactory that a suggestion is all that can be obtained from them. His sixty-sixth invention is a steam-engine for raising water, which he thus describes :-"I have invented an admirable and forcible way to drive up water by fire; not by drawing or sucking it upwards, for that must be, as the philosopher terms it, infra sphærum activitatis, which is but at such a distance. But this way hath no bounder if the vessel be strong enough; for I have taken a piece of whole cannon, whereof the end was burst, and filled it three-quarters full of water, stopping and screwing up the broken end, as also the touch-hole, and making a constant fire under it; within twenty-four hours it burst, and made a great crack. So that having a way to make my vessels, so that they are strengthened by the force within, and the one to fill after the other, I have seen the water run like a constant fountain stream forty feet high. One vessel of water, rarified by fire, driveth up forty of cold water, and a man that

tends the work has but to turn two cocks; that one vessel of water being consumed, another begins to force and refill with cold water, and so 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."

mentators.

Lord Worcester has given no description of the engine he invented, but as it is easy, with our present knowledge of steam and its applications, to design one meeting all the conditions of his statements, the lack of precise information has been supplied with conjectures by his comThere is one important particular in which he is distinguished from all the inventors who preceded him. It will be observed that in the experiment of Solomon de Caus, the effect obtained was immediately connected with the vessel in which the steam was generated; but in Worcester's engine the steam was conducted from the vessel in which it was generated to the work it was required to perform. This is the only principle which could have led to the invention of the present steam engine, and as far as we can understand the evidence to be collected from the works of inventors, who too often rather hint at their discoveries than describe them, the history of that mighty contrivance begins with the marquis of Worcester.

M. Arago's remarks upon the claims of De Caus and Worcester, though somewhat captious, are worthy of notice, as representing the opinions of French authors upon the origin of the

steam engine. "You have been,” he says, "made acquainted with the invention for which France and England have contended, as in times of yore seven cities of Greece, in their turn, arrogated to themselves the honour of having been the birthplace of Homer. On the other side of the Channel, all have concurred in attributing the merit of it to the marquis of Worcester, of the illustrious house of Somerset ; on this side of the strait we maintain that it belongs to a humble engineer, almost altogether overlooked by biographers, viz., Solomon de Caus.

"The marquis, being seriously implicated in the intrigues in the latter years of the reign of the Stuarts, was imprisoned in the Tower of London. One day, as the story goes, the lid of the pot in which his dinner was cooking suddenly rose. What can a man do in such a case but think? The marquis then thought about the strange phenomenon he had just witnessed. Then it occurred to him that the same force which had lifted the lid might become, in certain circumstances, a useful and convenient power. After regaining his liberty, he explained in 1663 the means by which he thought he could put his idea in practice. These means are, in all their essential points, the bomb-shell half full of liquid and the ascending vertical tube."

Although we have no evidence that sir Samuel Morland did anything to improve the mechanical construction of the steam engine

his name must not be omitted in a historical description of the contrivance. His reputation may not have extended to the circle of general readers, but he is well known to those who have studied the progress of hydraulic engineering. He was appointed master of the works by Charles II., in the year 1680, and was the inventor of several ingenious scientific contrivances. His right to be mentioned in connexion with the progress of the steam engine is founded upon a passage in a manuscript work, written in French, and preserved in the British Museum. "Water," he says, "being converted into vapour by the force of fire, these vapours shortly require a greater space (about 2,000 times) than the water before occupied, and sooner than be constantly confined would split a piece of cannon. But being duly regulated according to the rules of statics, and by science reduced to measure, weight, and balance, then they bear their load peaceably, (like good horses,) and thus become of great use to mankind, particularly for raising water, according to the following table, which shows the number of pounds that may be raised one thousand eight hundred times per hour to a height of six inches by cylinders half filled with water, as well as the different diameters and depths of the said cylinders." This is, as far as we know, the first attempt ever made to measure the expansive force of steam and its working power, and it is singular that Morland's experiments should have brought him so near the truth. M. Arago