The same class of mechanical engineering as that referred to in the above example is that involved in the design and construction of in dustrial plants of various kinds, such as cot ton- and woolen-mills, bleacheries, paper-mills, rubber-mills, machinery and other manufac tories, this branch of the profession being com monly known as mill engineering. In all of these cases the elementary parts consist of the power plant, which is sometimes operated by steam, sometimes by water and often by both, the machines in the mill or manufactory and the pulleys, shafting and belting required to transmit the power from the one to the other. The work of the mechanical engineer in these plants consists in properly assembling the vari ous machines so as to perform their functions, the selection of an appropriate power plant and the proper design and arrangement of the transmitting apparatus required for operating them.
The work of the mechanical engineer is of paramount importance in the construction of steamships. Not only does the design of the boilers and engines on which the whole opera tion of the ship depends originate with him, but he is also concerned in the design, loca tion and connection of the multitude of auxil iary steam appliances which abound through out the vessel and which contribute so much to the comfort of the passengers. The mod ern steamship is required to contain all the appointments of a first-class hotel. The serv ices of a mechanical engineer are many times more needed in its design and construction than in that of a hotel, for the reason of the con tracted space in which the machinery is neces sarily enclosed.
One of the most important industries in which the mechanical engineer is a leading figure is that of the steel-rail-mill. Here the plant, which is distributed over many acres of land, embraces immense blast furnaces where the pig iron is made, elevators by which the raw material is lifted to the top of the fur naces, blowing engines which produce the air blast required at the base of the furnace, con verters in which the iron is changqd to steel, hydraulic lifts by which the converters are manipulated and the steel blooms moved to cars, trains of rolls with their powerful direct connected driving engines where the rails are rolled from the masses of white-hot metal, together with their reheating furnaces and, in addition to all these, the extensive boiler plants and the system of piping and other apparatus required for conveying and supplying the boilers with waste furnace gases, on which they largely depend for fuel. The mechanical engineer who lays out and assembles the parts of which such a plant is composed has a task the magnitude of which is commensurate only with the importance of the interests involved.
Since mechanical engineering includes in its scope not only the proper design and con struction of machinery, but also its satisfactory performance, one branch of the profession re lates to the determination, by means of suit able tests, whether the desired performance has been realized. This has especially to do with boilers, engines, turbo-generators and other apparatus using steam, which the engi neer requires to be installed under specific guarantees of performance. The performance of boilers in the matter of economy may be specified in terms of the number of pounds of water evaporated per pound of coal, and, in that of capacity, in terms of the number of horse power developed, while that of the en gine or turbo-generator may be specified as the number of pounds of feed water or dry steam consumed per unit of power per hour. The performance tests require the determination of the quantities stipulated, by actual measurement of the coal, water, steam and power under working conditions. Another branch of me chanical engineering, in a similar line, relates to the testing of materials used in construc tion, the object being to determine whether they have the requisite strength and physical char acteristics. A sample or specimen of the ma
terial is placed in a testing machine and sub mitted to an actual breaking force and the amount of strain ascertained by measurement.
Having now given some explanation re garding the character of the profession of me chanical engineering, the question naturally arises as to the qualifications needed to make a success of such a profession. It hardly needs to be said of this profession more than of another that the one who adopts it should do so not merely as a means of livelihood, but be cause his tastes lie in the direction of mechan ical pursuits, if, indeed, he does not love the profession for its own sake. No one should enter the profession who is not fond of machinery, who is not a ((born as the saying is, or who is not deeply interested, to say the least, in every kind of machine. But apart from natural inclinations there are quali fications that especially fit one for the work of a mechanical engineer. He should have a technical education so as to be thoroughly grounded in the principles of mechanics. He should not only understand these principles but he should know them by heart. He may or he may not remember the formula derived from the principle, but the principle itself should ever be at his finger's end. He should be familiar with mathematics, geometry and trigonometry. He should know the strength of materials alb' be able to calculate the strains occurring in structures and in machines, both at rest and in motion, so that he may design them with the proper amount of strength, or, if already designed, that he may be able to prove that they are of sufficient strength for any purpose he may desire to use them. He should know their behavior under varying con ditions and should be able to detect their points of weakness and know the best methods of strengthening them when they fail. He should be a draughtsman and, what is the draughts man's next neighbor, an inventor. He should know the processes involved in the work of the patternmaker, founder, blacksmith and machinist. He should know how to erect machinery and how to operate it after erection. He should know the practices of the trade and he should know the various articles concerned in mechanical operations which can be bought in the market, and, in a general way, their cost. He should be familiar with the dif ferent kinds of boilers, engines, turbines, pumps, water wheels, etc., in the market and their relative advantages. Not the least in im portance should he be in the prin ciples of steam engineering and the laws which pertain to the generation and use of steam, not only for the operation of engines of various kinds, but for the various kinds of steam heat ing. He should be familiar with the steam engine indicator and be able to test a boiler or engine for capacity and economy. He should be well versed in hydraulic, pneumatic and elec trical machinery. He should know about the construction and operation of the various ma chines of the plant he has assembled, so as to be able to judge of the correctness of their de sign and construction and whether they per form their functions in a proper manner and according to the specified requirements. He should be able to prepare detailed specifica tions of the work he plans, and he should pos sess sufficient literary ability to draw up a suit able report upon any question that may arise regarding the work he is called upon to per form and pass judgment upon the comparative merits of different makes of machines required for a given purpose or of the different modes of carrying on given processes. In a word, the mechanical engineer must be skilled by observa tion, by study and by experience in the science and art of the profession from beginning to end.