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is nearly filled up by manual exertions to make

provision for the day that is passing over them," a want of leisure must prevent the greater number from consulting the numerous volumes in which the facts of its history lie scattered-even supposing that their means permitted their incurring the great expense at which this information could alone be purchased.

In a plan, therefore, which embraced so wide a field, and which was yet to be brought within the reach of inechanics in general, the distinguishing features only of each apparatus could in most cases be noticed; the details of many engines are therefore omitted, where they may be similar to any one previously described, or where their office and action may be easily understood by what has gone before: this omission has also been sometimes made in the Figures. Practical men, however, will not object to a very plain matter not being repeated, and general readers, (should any light on this volume,) by referring to the Figures, it is hoped, will find no difficulty in filling up the description: but to both classes of readers an inspection of a Figure will give a clearer idea of the action of machines, (nothing else can explain their construction,) than the most lengthened description ; -a line of engraving is worth pages of letter-press in the explanation of machinery. It was under this impression that so great a number of Figures was thought necessary, as are given in this volume Some of these Figures have been selected with a view to give an idea of the appearance of the Steam Engine

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at various times; and others to explain ‘its action, without any pretensions beyond that of mere explanatory diagrams.

The same reasons which prompted the omission of descriptions of some of the détails, have applied to the exclusion of merely theoretic disquisition or inference from these pages. This will not probably be objected to, since it so happens that the little which has been done by learned men on this subject is of no practical mark or likelihood. Twenty years ago Hornblower remarked, “that the most vulgar stoker may turn up his nose at the acutest mathematician in the world, for, (in the action and construction of Steam Engines,) there are cases in which the higher powers of the human mind must bend to mere mechanical instinct;" and the observation applies with greater force now than it did then.

We know not, therefore, how the remark has originated, or whats philosopher” first claimed for theoretic men any part of the honour of being instrumental, even indirectly, in the perfecting of the Steam Engine; or who gave currency to the phrase of its “invention being one of the noblest gifts that science ever made to mankind !!" The fact is, that science, or scientific men, never had any thing to do in the matter. It was a toy in the hands of all the philosophers who preceded Savery, and it again must become à toy before the speculations of Bossut, the ablest and latest of the philosophers who have written on the subject, can be made to bear upon it. Indeed, there is no machine

or mechanism in which the little that theorists have done is more useless. The honour of bringing it to its present state of perfection, therefore, belongs to a different and more useful class. It arose, was improved and perfected by working mechanics and by them only; for tradition has preserved to us the fact of Savery having begun life as a working miner;

-Newcomen was a blacksmith, and his partner Cawley a glazier ;-Don Ricardo Trevithick was also an operative mechanic; and so was the illustrious Watt, when he began, and after he had made his grand improvements.

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