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sertions of others, has expressed his desire and intention of repairing the injustice he has done to our countryman.

The fact relative to Mr Bettancourt's invention, we believe to be as follows. When that gentleman was in England some years ago, he had an opportunity of examining the engine at the Albion mills; and the principle of the engine was explained to him on the spot, either by Mr Watt or Mr Boulton. Considering how many men were occupied in the mill, and dependent upon it, it was not to be expected that either of these gentlemen should request the proprietors to stop the machine, merely that a stranger might gratify his curiosity by a minute inspection of the parts. Mr Bettencourt, therefore, saw the machine only at work; but we do not believe that the concealment of any part of the structure was intended. In fact, there was nothing in the construction of the double engine, which should not have been evident, upon mere external inspection, to any one who understood Mr Watt's single engines, which Mr Bettancourt had a full opportunity of doing, by examining that made by them for Messrs Perrier, and erected at Chaillot in the year 1779, to supply the city of Paris with water, This, which was a single engine, has continued to work there ever since, and is minutely described by Mr Prony. The inspection of the parallel motion in the engine at the Albion mills, naturally suggested to Mr Bettancourt the notion of steam, by its elasticity, forcing the piston of the engine up as well as down. To an intelligent engineer, the means of producing this effect could not be long of presenting themselves.

What Mr Gregory has said (p. 394) of Wolf's engine, appears to us very unsatisfactory. We do not believe that Mr Watt ever said or thought what he is here stated to have done; which appears to us totally inconsistent with all his experiments and inferences.

Another point, which we conceive to be very improperly treated by Mr Gregory himself in the work before us, is the contrivance of what is called the parallel motion in Mr Watt's double engine. This motion is brought about by forcing a bar, of a given length, to move so, that its two extremities shall be in the circumferences of two circles given in position, which circles have their convexities turned opposite ways, or towards one another. In a bar so circumstanced, certain points may be found which describe lines that, for a considerable extent, do not differ sensibly from straight lines. Such a position is easily given to the two circles, that the lines just mentioned shall be perpendicular to the horizon; in consequence of which, a bar or rod that is fixed at any of the points describing those lines, wil be drawn perpendicularly up, and forced perpendicularly dow VOL. XIII. NO. 26.


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as the pump rods are required to be in the engine with the double stroke. This very ingenious and masterly contrivance was first employed in Mr Watt's engines; and yet, in Mr Gregory's article of Parallel Motions, the name of Mr Watt does not once ocWe cannot but think that this is a remarkable instance of want of candour, and very unlike the treatment which one ingenious man is bound to give to another. The article, too, may be accused of being superficial, as well as uncandid. Why was not the nature of the rectilineal motion, produced by this contrivance, more accurately explained? Why did not the author inform his readers, as his geometrical knowledge surely could not but enable him to do, that the line described by the points in the beam above mentioned, is not, strictly speaking, a straight line, but is the part in which a curve, of a high order, has a contrary flexure, and passes from being concave on one side to become concave on the opposite? Why did he not explain in what manner the equation to this curve can be found, and what are the practical inferences that might from thence be deduced? This would have been the more worthy of a mathematician, that the practical solution of the problem at present in use is purely tentative, and the result of an experimental, not of a geometrical construction.

Concerning the principle which directed Mr Watt to the contrivance of this motion, different representations have been given. One of these, supported by the authority of Prony, is, that he was led to it by the consideration of an instrument used for describing a great variety of lines on paper, known by the name of Suardi's pen. Now, we must say, that we cannot but consider this as extremely unlikely, and that we could not easily be brought to credit it, except on the direct testimony of Mr Watt himself. It is very true, that Suardi's pen, if known to him, may have suggested the idea that it was possible to describe, by a continued motion, certain curves, portions of which, where the curvature changes its direction, do not differ sensibly from straight lines. This, however, was not a piece of information very material to be received, or such as any man accustomed to the inspection of geometrical figures, could have any occasion to look for from without. But the information to be obtained from Suardi's pen, could go no further than this, when considered relatively to the conditions under which the problem of the parallel motion was to be resolved in the steam engine. In Suardi's instruament, the complication of wheels and pinions, and the consequent description of cycloids and epicycloids, may be continued without end. When any line whatever, therefore, is described by this instrument, it is in consequence of a vast complication of motions,


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such as Mr Watt, or any man working upon the scale that he did, and with the means he must employ, could have no power to imitate. The complicated process of Suardi, if it could have had any effect, must have led an engineer to despair absolutely of describing similar lines by the few simple motions which he had it in his power to produce. Far from suggesting the means of overcoming the difficulties, it would have deterred him from any attempt to overcome them.

We may conclude, therefore, with great probability, that it was not in this way that the discovery was made. There is a much more natural and more obvious view of the matter, by which we are persuaded that Mr Watt was directed; but our conjecture has a defect, unpardonable, we believe, in the eyes of our author and his friends; it gives the whole merit of the contrivance to Mr Watt himself.

The reasoning we suppose to have passed in his mind, is the following. By means of the angular motion of the beam of the steam engine, it is easy to make any point move in the circumference of a circle with a reciprocating motion. If it is the end of a beam or bar which is made to move in this manner, the other end of it may also be made to move in another circle, by fixing it with a joint, to a radius which has its other extremity fixed to a given point. We shall thus have a beam of a given length, moving up and down with its extremities in circles, which turn their convexity towards one another. Between these two extremities, therefore, it should seem that there must be one point that will have the convexity of its path turned neither way, if one may speak so; that is to say, will be neither concave nor convex, but straight for a certain portion of its ascent and descent. This was a simple view of the matter, such as much practice in the construction of machinery would very readily suggest to a man of ingenuity, used to reflect on the gradual transition by which all changes in the quantity, or direction of motion, are effected. If, after taking this general view of the matter, he should make an appeal to a geometrical construction, he would find his conjecture completely verified, and would soon perceive in what manner the data of the problem might be so varied as to give to the line described, whatever position was required. We are very fully convinced, that it was in this way that Mr Watt's discovery was made; and we shall continue to believe so, till we have his own evidence for the contrary. It is certainly more probable that he was guided by the simple and direct, though perhaps refined reasoning just mentioned, than by any thing so circuitous and indirect as the study of a complicated machine, with which the thing to be found out is very remotely, if at all connected

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But, however the invention was suggested, it must on all hands be acknowledged, that it possesses as large a share of mechanical excellence as any single contrivance whatsoever ; and does as much credit to the ingenuity of the inventor.

On the whole, when we look back on what is here so improperly called a description of the steam engine, and which, in reality, is nothing else than a coarse and illiberal invective against the inventor, full of hints and surmises that cannot be supported, or of affirmations that can be completely disproved;-though we can form some notion of the motives by which the author was actuated, we are utterly at a loss to discover those by which the editor was influenced, or to find out any argument by which he can justify his conduct. Had the memoir he has now chosen to give to the world contained any valuable and new information, the manner, however clumsy and rude, might have been overlooked; though the attempt to do injustice ought not, even on that account, to have been tolerated. But we can perceive no inducement whatever for the insertion of the memoir. Considered as a description of a mechanical contrivance, it is exceedingly defective; its parts are ill arranged, and loosely connected; the reasonings vague, and the information inaccurate; so that it is in every thing a model of the taste, temper, and style which ought carefully to be avoided by any one who would explain the principles, or relate the history of improvements, whether in science or

in art.

The man who countenances such illiberal proceedings, not only injures an individual, but, in reality, does all he can to obstruct the progress of those improvements which he professes to explain. It is of the utmost consequence to that progress, that every inventor should be as much as possible assured of the reward to which his discoveries naturally entitle him. In estimating the extent of that reward, we must give the first place to the satisfaction a man feels from the exercise of his own ingenuity, from the activity he exerts, and from the prospect of being serviceable to mankind. This greatest and most direct reward, which nature has inseparably connected with the exertions of genius, it is happily not in the power of malignity or accident to disappoint. The second branch of the reward, is the fame, the honour and reputation, to which invention in the sciences or the arts has a just claim. The emolument and wealth to which it may occasionally lead, comes only in the third place; and, with the men most likely to invent or to discover, will readily be postponed to both the other two.

These two last branches of the reward of merit, are not, Kke the first, necessarily or constantly secured to it. The se


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cond, indeed, is of peculiar delicacy, and easily affected by envy and misrepresentation. Of this, Mr Watt has experienced an abundant share; and there are certainly few men whose claims to originality have been subjected to so severe a trial, or established by so large a body of legal evidence. We rejoice that he is now in the possession of the ease and affluence to which the services he has rendered to his country, and to the world at large, do so well entitle him. It is not the business of, a friend of science; of one interested only for truth and justice, to trouble the repose of an eminent man, retired from active life, and enjoying the fruits of a well earned and justly deserved reputation.

ART. IV. Statement of the Proceedings of the Society for the Suppression of Vice, from July 9. to November 12., read at their General Meeting, held November 12. 1804. With an Appendix, containing the Plan of the Society, &c. &c. &c. London. 1804.

An Address to the Public from the Society for the Suppression of Vice, instituted in London 1802. Part the Second. Containing an Account of the Proceedings of the Society from its Original Institution. London. 1804.

A SOCIETY, that holds out as its object the suppression of vice, must at first sight conciliate the favour of every respectable person; and he who objects to an institution, calculated apparently to do so much good, is bound to give very clear and satisfactory reasons for his dissent from so popular an opinion. We certainly have, for a long time, had doubts of its utility; and now think ourselves called upon to state the grounds of our distrust.

Though it were clear that individual informers are useful auxiliaries to the administration of the laws, it would by no means follow, that these informers should be allowed to combine,-to form themselves into a body, to inake a public purse, and to prosecute under a common name. An informer, whether he is paid by the week, like the agents of this Society-or by the crime, as in common cases-is, in general, a man of very indifferent character. So much fraud and deception are necessary for carrying on his trade, it is so odious to his fellow-subjects,-that no man of respectability will ever undertake it. It is evidently impossible to make such a character otherwise than odious. A man who receives weekly pay for prying into the transgressions of mankind, and bringing them to consequent punishment, will always be hated by Y 3


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