CATECHISM OF THE STEAM ENGINE, ILLUSTRATIVE OF THE SCIENTIFIC PRINCIPLES UPON WHICH ITS OPERATION DEPENDS, AND THE PRACTICAL DETAILS OF ITS STRUCTURE, IN ITS APPLICATION TO MINES, MILLS, STEAM NAVIGATION AND RAILWAYS. With various Suggestions of Emprovement. BY JOHN BOURNE, C.E. THIRD EDITION. LONDON: LONGMAN, BROWN, GREEN, AND LONGMANS, PATERNOSTER-ROW. PREFACE. THE present work is not intended as a substitute for the quarto Treatise on the Steam Engine, which I lately published, but is rather to be regarded as an introduction and in some measure also as a supplement to that work. Notwithstanding the existence, therefore, of the larger Treatise, it appeared to me that a work upon the steam engine, which in a moderate compass should give an outline of the whole subject in its practical aspect, would still be of much utility. There are no doubt many compendiums already existing which profess to accomplish this object; but I have not met with any which were calculated to satisfy even the most moderate expectations. Most of them are mere compilations from theoretical authors, and abound even with scientific errors, whilst indicating the absence of any practical acquaintance with the subject; so that they possess but slender claims upon the attention of the engineer, or indeed of any one desirous of ob a |