A COURSE IN NAVAL ARCHITECTURE.

BY CECIL H. PEABODY,

Professor of Marme Engineering and Naval Architecture, Massachusetts Institute of Technology, Boston, Mass.

The larger part of the commerce of the world is now carried by iron steamships, and the tendency is more and more toward the use of iron (or steel) for the material for construction, and of steam as the mode of propulsion; though in some places and for certain purposes, wood is still preferred and sails are still used.

The construction of iron ships and the fitting of their machinery is clearly a branch of construction engineering; even more so is the management of the yards in which such ships are built.

Following the precedents of the transition period when ships were built by ship carpenters and engined by machinists, there is a tendency to make a sharp division between the building and engining of a ship; one branch is called naval architecture and the other marine engineering. In reality the difference is like that between engine building and boiler making, which are distinct trades, though both engine and boiler are commonly designed by one engineer. Without question, the final responsibility for the ship and her machinery should rest with one man who should be master of both branches of his profession.

This paper will consider that a course in naval architecture should give a sound and well rounded training in engineering as applied to ship building, including both hull and machinery.

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The modern tendency toward specialization is found exemplified in the engineering profession, and is reflected by schools of engineering, which offer courses in civil engineering, mining engineering, electrical engineering, etc., and commonly the courses are sub-divided into options. But every competent engineer is first an engineer and afterwards a specialist, and in like manner we find that any course in engineering must first of all give the great body of fundamental principles underlying all engineering work, and then add specialties and options. That which is common to all engineering courses is both larger in amount and more important than that which is different.

All this is so evident as to appear a truism, and yet time and space may be saved by its statement, because there is a general concensus of opinion concerning what forms the main body of instruction in engineering. It is sufficient to name mathematics, chemistry, physics, applied mechanics and strength of materials, and to add modern languages, English literature, history and political economy, to account for the larger part of the time and labor of students in those engineering schools which aim to make men, as well as to train engineers.

Thus we find the major part of our course in naval architecture already laid out for us.

The naval architect has much to do with machinery in all the processes of shaping and working the material into the ship, and must deal with the generation and application of the power which is to drive the ship. To the main body of instruction must by added

mechanism, dynamics of machines, thermodynamics and the theory and practice of steam engineering.

It is not necessary to say at this day that the instruction mentioned should be accompanied by work in laboratories of chemistry, physics, applied mechanics and steam engineering, nor to call attention to the advantage of shopwork in wood and iron.

We may add to the work already laid down the special study of the marine engine and the application of its power to propellor or paddle wheels. Attention should be given to varieties and details and to methods of construction and erection of marine engines. When quick-running engines are used the dynamic action of the moving parts becomes of great importance on account of the stresses and vibrations that are liable to be set up. The principles to be used for an investigation of this action will be taught in the dynamics of machines, but the detailed application to an important engine may well form a part of the special study of marine engines.

The subject of drawing has been left for separate mention in order that it may receive greater emphasis. The ability to represent constructions by drawings and to get from drawings the conception of form and solidity is of prime importance to all engineers; to the naval architect most of all. The importance of descriptive geometry as preliminary training for this purpose can scarcely be overrated, not merely that the propositions and problems are likely to occur in ship and engine drawings, but even more on account of the ability it gives to conceive geometrical and irregular forms, to represent them by their pro

jections, and to rapidly and correctly read all kinds of mechanical drawings.

A student of naval architecture should make enough machine drawings to become familiar with the methods; his training for facility and finish will be given mainly by the considerable amount of ship drawing that must form part of the course.

The body of facts, experiments and observations, which, with the proper mathematical investigation and reduction, form the theory of naval architecture, is neither very large nor very difficult. All that is accepted as certainly known, whether or not it has or can be used in practice, can be taught in its entirety in a four-years' course of study, together with all the other subjects that have been named as essential for the proper training of a naval architect. It appears to be very desirable that the course in naval architecture should form a regular four-years' course on the same basis as the courses in mechanical and electrical engineering. Of course students who are able and disposed will find it advantageous to take five years and so broaden their training by rounding out their work in mechanical engineering and by taking electricity; but it is true in like manner, that any engineering student will find it advantageous to take two courses if he can.

The special instruction in naval architecture may well begin with a description of the framing, details and method of construction of ships in wood and iron (or steel), which may be given in the second or third year of the course. It might come earlier except that the mathematics required for a proper understanding

of the theory of naval architecture can hardly be attained before the end of the second year, and lack of continuity in the special work of the course is undesirable.

This descriptive work need not be very extensive or minute; it should be enough to enable the student to rightly comprehend other work of the course which presupposes such knowledge, and to recognize work that he may see in process of construction in shipyards. His knowledge of the art of shipbuilding must finally be learned in practice in the shipyard and drawing office. It will be of the greatest advantage to students to get some experience in shipyards or drawing offices in summer vacations, but opportunities for such work will be obtained by a few only.

The theory of the properties of ships may be divided into two parts, statics and dynamics; the first deals with form, displacement, stability and strength; the second with waves, rolling, resistance and propulsion. The first part of statics is mainly geometrical in nature, and can be presented in a certain and definite manner. The second part, various in form and nature, is incomplete in many places and exists largely in the form of the original memoirs. Much of it must be given in its incomplete condition, and this adds. to the difficulty of both the student and the in

structor.

The determination of the best form for a certain ship has been the result of a slow and laborious evolution, so far as we really know anything about this matter. The only attempt at a theory, that by ScottRussell, is now discredited. Examples of models and