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engine expressed in numbers, of which the ordinary strength of a horse is the unit. This, no doubt, is not in itself very exact, the unit being large, and subject to some variation. Relatively to the purpose for which it was used, it was however sufficiently correct; and on this, as on many similar occasions, a more minute measurement would have been less useful. If a historian would express the interval of time between two different events, he is in general satisfied with counting the number of years and it would be a useless affectation of accuracy to reckon up the months, days, hours and minutes, that must be added or taken away, in order to measure the aforesaid interval with mathematical exactness. So, also, if a man were to ride post from London to York, it would serve his purpose as well to know the distance of these cities in miles, as in feet, inches, and decimals of an inch.
Boulton and Watt, however, have not left the matter in a state that can be accounted incorrect in any case, but have given to it all the accuracy that can be required, when, from the result of experiments made with the strong horses employed by the brewers in London, they have assumed, as the standard of a horse's power, a force able to raise thirty-three thousand lib. one foot high in a minute; and this, no doubt, was meant to include an allowance of power sufficiently ample to cover the usual variations of the strength of horses, and of other circumstances that may affect the accuracy of the result. This determination, we think, could not be unknown to Mr Gregory, and certainly not to his coadjutor. If, in forming the estimate just mentioned, the power of a horse is rated, as we think it is, above the ordinary average, this circumstance cannot be complained of by the public, as it tends to represent the advantage of the engines less than it will be found in real practice.
It is impossible not to advert to the great inconsistences into which the author of the memoir we are now considering has been led, by a desire to appear candid, and a strong propensity to be quite the contrary. He says, that he is not disposed to detract one atom from the advantage resulting to the community through the perfection of Mr Watt's engine;' and again,' that he does not mean to withhold the acknowledgment, that, through Mr Watt's means, the steam engine now ranks foremost among the productions of the philosophical and mechanical world. Yet, in another place, he says, that it is still in the minds of some yet in 'existence, that the first engines which were erected by Mr Watt, exhibited but miserable specimens of his mechanical abilities.'
It is not easy to reconcile these passages, or to understand how. the engineer, to whom the most perfect mechanical contrivance of the present age is admitted to owe its improvement, should
have given at any time, and especially after he had made those improvements, a miserable specimen of mechanical ability. These things are obviously inconsistent, and could hardly have come together in the mind of any body, but one who affected the character of justice, only that he might give a deeper wound, and render his injustice more efficient.
Mr Hornblower remarks, at page 361, That some sterling ⚫ acknowledgments are due to Mr Watt's coadjutors, of which he availed himself in a region of rare talents. It may be observed, that, by a region of rare talents, the author probably means a region in which talents were not rare. Now, as to the indefinite charge here made against Mr Watt's candour, it is evident that who lives in a civilized age, and among men every man. of talent and ingenuity, may have such a charge brought against him; for he must, doubtless, be indebted for much of his knowledge and attainments, both to his predecessors and contemporaries. There are few men, like Napier or Bacon, of whom it can fairly be said that they owed nothing to those around them, and that, in their inventions or their discoveries, no one whatever can claim the smallest share. This, however, we believe, to be as nearly true of Mr Watt's inventions, as it can be of any, in an age where art and science are so highly improved, or so extensively cultivated, as in the present. From the first experiments, when the model at Glasgow College was put into his hands, to the last improvement made on his engine, as it now exists, we believe the whole series to have been the work of his own genius. The more carefully one studies the history of the steam engine, the more he will be convinced of this fact; and it is indeed reasonable to expect that it should be so: for, after the improvement of condensing in a separate vessel was made, the subsequent improvements lay so much more in Mr Watt's way, than in that of any other person; they were things that could so little be struck out by sudden efforts of ingenuity; they must, from their nature, be the fruit of so much patient and profound reflection, that Mr Watt, with inventive powers much inferior to those which he really possesses, had a chance of many hundreds to one, in his favour, that he would be the first to discover, and the first to remedy any imperfection in a system of contrivances which he had studied with so much diligence, and which was, in fact, the creation of his own genius.
We must be permitted to remark, too, that Birmingham was not the first region of rare talents, to use the phrase of Mr Hornblower, which Mr Watt had had the good fortune to inhabit. At Glasgow, he lived in a society of ingenious men, and had for his particular friends the late Professor Robison and Dr Black. The
former was, no doubt, a very young man; and his fertility of invention, though great, could not be supposed to give much assistance to an experienced artist. Dr Black, on the other hand, was older than Mr Watt, and was at that very time engaged in the discovery of the doctrine of latent heat, so analogous in some respects to the objects of Mr Watt's inquiry. But, notwithstanding this, and though one of Mr Watt's most important discoveries, the great quantity of cold, if we may use that language, necessary to condense steam, might have been deduced from the doctrine just mentioned, had it been then fully established; the truth is, that he was led to it from his own experiments, independently of all theory, and before he was acquainted with the principle which Dr Black was then, as we may say, in the very act of discovering. This we state expressly as appearing clearly from some original papers which we have had occasion to examine, and also from recollecting, as some of us do, the account which Dr Black, with the modesty and candour which so strongly marked every part of his character, never failed to give, when the history of Mr Watt's discoveries and his own became the subjects of conversation. He seemed always to feel over again the pleasure he had first experienced, when he understood the coincidence between the results of Mr Watt's experiments and his own. The truth, therefore, appears to be, that Mr Watt's result was deduced from his own experiments alone, though the explanation of it was derived from the theory of Dr Black.
Mr Hornblower, in his style of loose and angry invective, has thrown out many reflections on the author of the article Steam Engine, in the Encyclopædia Britannica; and he is not ashamed to call that article a farrago of absurdities. In two things we are ready to admit that he has corrected that article, viz. in what respects the leathering of the pistons of a steam engine,—and again, in what respects the density of steam; in which last, however, he knew that the author had already corrected himself. Now, these two mistakes could not have concealed from any one who was not under the influence of excessive prejudice, the great body of valuable facts, ingenious deduction, and useful inform→ ation of every kind, that are generally acknowledged to be contained in the article above mentioned, when connected with its Supplement. The real objection, however, in the eyes of Mr Hornblower, is, that the article we are speaking of was drawn up by a friend of Mr Watt's, an admirer of his talents, and a man every way qualified to appreciate them. What he has said, is the tribute paid by one man of genius to another; and there is therefore no wonder that it should not express the
sentiments of Mr Hornblower. That gentleman, however, may have the apology of knowing nothing of Mr Robison but the article just mentioned. Mr Gregory certainly has not the same apology for admitting a coarse and turgid invective, directed against an author with whose merits he cannot fail to be acquainted, and of whose productions he must often have availed himself. *
At page 391, a steam engine is described with great praise, the same with one that has been mentioned in the Encyclopædia Britannica, and commended; and is one for which a patent was taken out by Mr Jonathan Hornblower of Penrhyn in 1781. In the account, however, one circumstance is omitted, which is very material in the history of this engine; viz. that in the year 1799, it became the subject of an action, as an infringement of Mr Watt's patent; and that the miner who had used the engines of this construction, paid the portion of savings in fuel claimed by Messrs Boulton and Watt for the use of their invention, rather than risk the event of a lawsuit. It should, besides, be observed, that if this engine merits the eulogium bestowed upon it, it seems singular, that not one of the kind has since been erected, though all legal obstructions were removed, by the expiration of Mr Watt's' patent in the year 1800...
A similar omission is made, in the description of another engine, viz. that erected by Messrs Murray and Wood in 1802. Neither the author of this article, nor the editor, have stated what is well known to be the fact; viz. that the nozles or steamvalves, there described as having the stem or spindle of the one passing through the spindle of the other, and ascribed to Messrs Murray and Wood; as also, the method of opening these valves by a circular motion derived from the rotative shaft of the engine, had been previously used by Boulton and Watt, in engines which they had erected; and that the patent taken out in 1801 by Murray, for these and other pretended inventions, was set aside in 1802 or 1803, by a writ of scire facias, at the instance of the company just named.
In speaking of Mr Gainsborough, whom he supposes to have preceded
* In looking over the articles in Mr Gregory's two volumes, we have not observed that there is any very scrupulous correctness in the references to his sources of information. For example, the abstract of Coulomb's experiments, and the section on horizontal wind mills, are taken, with little variation, and no acknowledgment, from Dr Brewster's edition of Ferguson's Mechanics. The same is true of the article on the teeth of wheels, and part of the description of the thrashing machine, &c. Some sterling acknowledgments, to use the language of his friend Mr Hornblower, were surely required from Mr Gregory on such occasions.
preceded Mr Watt in the invention of cooling the steam in a sepa-
As to what regards Mr Gainsborough's invention, we shall not enter upon the merits of it: but, whatever these may have been, it is quite impossible that Mr Watt's idea of condensing in a separate vessel could be derived from that gentleman. Mr Watt, while he resided at Glasgow about the year 1764 or 1765, invented that method of condensation, as we have seen, and as is proved from a concurrence of the most respectable testimony. Mr Gainsborough's improvement, whatever it was, was posterior by more than twenty years.
After the preceding article is concluded, Mr Gregory himself gives an account of Mr Prony's statement, in his Architecture Hydraulique; where the French author has ingeniously contrived to found, in favour of Bettancourt, a kind of secondary claim to the invention of the double steam engine; and by devoting a considerable portion of one of the volumes of his elaborate and useful work to the description of the steam engines, which he states to have been designed by Bettancourt and executed by Messrs Perrier at Paris, he has succeeded in transferring to them, in the eyes of the greatest part of the continent, the credit of inventions which belong exclusively to Mr Watt. We should feel ourselves called upon to enlarge upon this article, did we not understand, from good authority, that Mr Prony, sensible of the error into which he has been led by the as