We are in receipt from the publisher, D. Van Nostrand, Nos. 23 Murray street and 27 Warren street, New York city, of a copy of a work on the steam engine indicator; being the treatise of Charles T. Porter, revised and adapted to American practice, by F. W. Bacon, M. E., Member of the American Society of Civil Engineers, with an appendix containing useful formulas and rules for engineers. Were we called upon to prescribe the best method whereby a student could gain, not only the most easy but the most thorough theoretical knowledge of the laws which govern the formation and expansion of steam and the application of steam to the performance of work in engines. we should unhesitatingly recommend a course of study with the indicator. l'he indications of this beautiful instrument not only tell what. is going on in the cylinder of an engine, but in doing this they lea'i the mind to the consideration of the fundamental principles of steam generation, as well as the doctrines of expansive force, latent heat, temperature, laws of condemsa-tion and radiation, and the subtile relations which all' the phenomena of steam bear to each other. Mr. Bacon has, in his revision of Mr. Porter's work, done the American engineering public a great service, and has supplied a valuable hand-book of reference and instruction. Mr. Porter's treatise has been for some time out of print, and the present revision has offered a good opportunity for the addition of much valuable matter, and the adaptation of the work to American practice. The work commences with a fall description of the indicator and the mode of applying it, and we are glad to see that Mr. Bacon has in this department been profuse in practical details which are apt to embarrass a novice. Next follows a discussion of the interpretation of indications, given in a plain and concise style, and perfectly comprehensible to men of ordinary intelligence. This part of the work contains a number of tables, by the use of which much of the lfIbor in reducing indicator cards is avoided. Mr. Bacon's method of determining where the true theoretic curve on a card intersects the ordinates is very clear, and will greatly assist beginners ; the numerators of the fractions being constantly the number of the ordinate where the steam is cut off, and the denominator the number of the ordinate, the length of wch is sought. This is well illustrated by a special diagram. A great variety of diagrams is given. A careful study of these diagrams cahnot fail to interest all who desire to understand the working of the indicator. We herewith produce two of them, one of which was taken from an English locomotive engine, and the other from an American locomotive. Fig. 1 is the English card, taken from the locomotive "Eagle," on the London and Southwestern Railway, in April, 1863. This diagram, with three others given by the author, are fair samples of a large number taken from the same locomotive. Fig. 2 is a diagram of a card taken from locomotive No. 50 on the Philadelphia, Wilmington, and Baltimore Railroad, in 1867. It was taken at; sixty miles per hour, the piston making 1,222 feet per minute, with 3055-46 revolutions. In regard to this diagram, the author remarks : "Notwithstanding this extraordinary speed tbe lines are all well defined showing distinctly the points of cut-off and release. A remarkable point in the diagram is, that though the pencil passed over it certainly twice or more, the lines are very near to each other, showing that even under this unprecedented speed ot piston, the instrument was uniform and reliable in its action. This is not a selected diagram, all others taken on the same trip show the same characteristics. Leaving the interpretation of these diagrams to engineers, we pass to the appendix, which c(jlUtains much useful information. We shall also make a single extract from this portion of the work, which will sufficiently show its practical character. The extract relates to the measuring of steam used for heating. " The engineer is often called to determine the amount of steam that is used to heat apartments, liquids, etc. This the indicator does not reveal directly, no further than it shows how much steam it requires fur a horse power; varied, of course, by the point of cut-off and its efficiency. "Under these circumstances we have followed the rule of Watt, which is to allow one cubic foot of water per hour for each horse power; hence we . measure the water condensed in the heating pipes in a given time, and estimate accord-lying "If it is inconvenient to reduce the water to cubic feet, it may be weighed, allowing 62'5 lbs. to the cubic foot, or it may be measured by the gallon, or 7'48 gallons per cubic foot. " When the steam pipe enters the vessel, and it discharges the steam directly into the liquid to be heated, the water then cannot bo caught to be measured ; in that case we measure the increment of its contents, and thereby find the quantity of steam condensed." On the whole, tl1e work is one well adapted to the use of scientific and practical engineers, and cannot fail to be an important help to any who seek a complete knowledge of steam and its applications.
This article was originally published with the title "The Steam Engine Indicator"