put the price equal to gas at $1.69 the company would earn 20 per cent. additional, making its profit in all 30 per cent. A further and most important saving can be made by heating the buildings by means of the exhaust steam from the engines, so that in winter but a part of the whole expense could be chargeable to the electric lighting, $8000 to $9000 might thus be saved, bringing down the cost to that of gas at $1.48 while affording seven per cent additional profit. The largest item of cost is lamprenewals and we may be reasonably confident that the average life of lamps will be greatly increased and that their cost will be much reduced. There seems to be therefore no reason why the electric light for domestic purposes should not at once be a paying investment, as it is known to be in numerous cases where isolated plants have been introduced in manufactories, and other places of business. TRAINING FOR MECHANICAL ENGINEERS1. By Prof. GEO. I. Alden, Worcester Free Institute, Worcester, Mass. [ABSTRACT2.] PROGRESS in education is secured by the aid of forces outside and above the schools. When a few have made discoveries in science or advancement in art or in engineering they have set a standard which must thereafter be the aim of educators. Mechanical engineering as taught in schools is subject to the general law of progress. While it is taking a high rank as a liberal profession and offers a broad field for the activity of the best powers of young men who enter it, yet it must look for progress to two main forces, 1This paper was presented in response to the announcement of the Secretary, that one or more sessions would be devoted to the discussion of the "Best methods of teaching mechanical engineering." Owing to a variety of untoward circumstances, other expected papers did not come to hand in time, but an exceedingly lively and interesting discussion was aroused. This was participated in by a number of prominent mechanical engineers and teachers and other scientists, and it was unanimously decided that the discussion must be continued. The following gentlemen were accordingly ap pointed a committee to secure the active coöperation of leading men in a fuller presentation and discussion of the subject at the next meeting: J. Burkitt Webb of Cornell University, Ithaca, N. Y., Geo. I. Alden of Worcester Free Institute, Dr. C. M. Woodward of Washington University and A. Beardsley of Swarthmore College. 2 Printed in full in the American Engineer, Oct. 3 and 10, 1884. viz., the influence of the scientific attainments and practical achievements of those foremost in engineering science and practice. A school for training mechanical engineers is properly a professional school, and should hold up its standard of professional training, in order that it may demand in candidates suitable preparatory, general training for matriculation. It should aim to fit young men for immediate usefulness in the profession, and to lay the sure foundations for a growth which shall enable them to take up the unfinished work of the engineers of this generation and carry it forward into the next century of progress. To aim at practical achievements is not enough; for the man is more than his profession. Scientific attainments are not alone sufficient. The ability to apply knowledge to practical ends is valuable in discipline as well as necessary to professional success. The necessary scientific attainments are more than mere knowledge of facts and principles. The evidence of such attainments is the ability- within a sufficiently wide range of inquiry-to give accurate answers to definite questions. To secure this ability the usual studies in the curriculum of the schools should be thoroughly taught by direct methods, with the aid of numerous and well selected problems, and laboratory work. The problems should be, as far as possible, actual engineering problems that the student may secure that complete assimilation and personal appropriation of the subjects taught throughout the course, which characterize the scientific attainments toward which the school should aim. The practical achievements of the engineer are closely related to machine-shop methods and practice. All his designs must be sent to the shop in a form consistent with such practice. To secure knowledge of machine-shop methods, limitations and possibilities, most schools have a practical or shop department in their engineering course. It is important that the successful engineers of the country should say what such a shop should be and what it should accomplish. The shop is made a department in the course in order to add to the school methods as well as to its facilities for instruction. It should not, therefore, be such an institution as would be developed by, or out of, the school. It should bring to the school its own methods and standards. It should be superior in all its appointments for practical, constructive and engineering work. It should have not only the tools, methods and facilities but also the business of a leading productive shop. It will then be able to adopt, in a full measure the modern methods of instruction aimed at in other departments. Its work will be in accordance with the economical principle of teaching analysis and synthesis in close connection. Work on real valuable products has elements of training which are lacking in work on simple isolated pieces. It cultivates practical judgment, gives valuable experience and available skill. The connection of the shop with the school is an advantage to the shop, and a stimulus to breadth and thoroughness in other departments. It promotes symmetry and harmony in the whole training without detriment to any of its qualities and economizes by variety of occupation the time spent in the school. About ten hours per week, spent in such a shop, will, in four years, give the student as much skill (and more general ability) in the shop, as a three years ordinary apprenticeship. This opens to every graduate a wide door to the engineering profession, giving at once opportunity for talent and independent self-support. Such practical attainments are secured by the construction in the shop of products for the open market. Only in this way will it be practicable to keep up the standard of workmanship and design and the practical methods of engineering practice. From fifty to one hundred thousand dollars for shop and equipment would give provision for instruction of 100 students, and from three to ten thousand dollars would be required for annual running expenses. Experience indicates that money expended, in founding and fostering such a shop department as above outlined, will yield a large return both to the individual students and to the profession. TOPOGRAPHY OF MACHINES. BY OBERLIN SMITH, M. E., Bridgeton, N. J. [ABSTRACT.] THERE is a serious lack of system in our machine-building practice regarding verbal descriptions of positions and motions. This causes ambiguity in both written and oral explanations; which are necessary, in new machines, in addition to drawings. An instance of this is where some member of a machine has a socalled front of its own, facing in a different direction from the main front of the machine. The remedy is to always assume one side as a front and let the fronts of all pieces, when in position shown on drawings, face in the same direction. Let left and right be rated by the hands of the operator as he stands in front of stationary machines facing them; and as he stands upon moving machines, such as boats, vehicles, etc., facing forward. This will give a relatively different position of sides in the two classes but it will make no difference if all views on drawings are plainly marked "front," "top," etc. Let all directions be defined, in the whole machine or a separate piece, as either "forward," "back," "right," "left," "up,” "down;" and all sides as "front," "back," "right," "left," "top," "bottom." Let all positions referred to some other point be "front of," "back of," "right of," "left of," "above," "below." Let all measurements be in rectangular directions if linear. If angular let them count from some rectangular line. By using these rules a designer can finish designs of intricate machines through his assistants, communicating by mail and even telephone. The writer is working out a system, as yet in a crude state, for carrying the above principles toward an ideal condition where a machine could be wholly described by figures and letters, without any drawings at all. Practically it would supplement, simplify and elucidate a set of drawings rather than wholly supplant them. The general idea embodied is to locate any desired point in a machine, or other object, by a perpendicular measurement from each of three "reference planes," all at right angles to each other and (usually) forming three adjacent sides of a cube exterior to the machine, each measurement being recorded upon the drawing prefixed by a letter U, R, or F, representing up, right or forward, respectively. This system has already been partially applied to taking measurements of old machines, to get data for making drawings, and has proved much superior to the random method usually practised of measuring from anywhere to somewhere. In plotting down such a survey as has just been referred to, it will be found of great benefit to use cross-ruled drawing paper, preferably graduated to inches, and their halves, quarters and eighths, the inch lines being the heaviest. These lines should be numbered from one edge of the paper each way, and their use is just as important as are the lines of latitude and longitude in copying a map drawing. The writer herein claims no new principles, but merely the applications of some very old ones, and as yet in a somewhat imperfect way, to the ordinary operations of machine shop practice. Such a reform as is here foreshadowed is most urgently needed as one of the means of systematizing the work of the mechanical engineer. It is, in fact, only the common sense use of methods which have long been employed by the geographer, the topographical-engineer, and even by the landscape-gardener and the railway contractor. DRIVEN WELLS. By J. C. HOADLEY, M. E., Boston, Mass. [ABSTRACT.] THE investigations of Darcy, Dupuit and Lueger, and the experimental determinations of Piefke and others, relating to the flow of water in porous earth, are recognized. Some unfounded assumptions, and fallacious theories and unsound explanations of these, by courts and experts, are pointed out. Description of the method of conducting experiments which should place in a clear and convincing light the truths of nature, relating to the flow of water from the natural height of the surrounding ground water, down an obstructed hydraulic slope, by gravity alone, to the depressed surface of the water immediately around the suction pipe of a pump and in wetting contact therewith, whether such suction pipe be driven or otherwise inserted in the ground, or put into the open water of an ordinary well : First, by pumping from actual tubular wells inserted in natural water-bearing soil, and marking the effect both as to the quantity of water obtained and slope of water-surface produced, in comparison with corresponding results by similar pumping from a small open well; and, second, by laboratory experiments with pumps, working under various conditions in artificial filtering tanks, supplied with appropriate measuring, indicating and recording appa ratus. 1 This paper is printed in full, with illustrations, in the Sanitary Engineer for De cember 4, 11, 18, 25, 1884. |