One of the leading problems confronting the mechanical engineer, whatever the special line in which he is engaged, is the re luction in the cost of production, and, what is allied to it, the attainment of the maximum result from machin ery with the least expenditure of money, time and labor. As machines and processes are in a continual state of improvement, and almost all lines of business are in a continual state of growth, it does not require many years to elapse after a piece of engineering work has been com pleted before it must be remodeled or enlarged to meet the demands of the times. This problem of reducing the cost of production is, therefore, one which is continually before him. In the de sign of an individual machine, the highest aim is to reduce the number of parts and quantity of material used to the smallest amount consistent with proper operation, and to run it at the high est speed which can he safely and successfully maintained. In arranging a plant for carrying on some industrial process, the aim must be to employ machinery wherever it is possible to save the labor of men, and assemble the machines so that the least number of hands and the least expense is required to change the raw material into the finished product. Following in the same direction is the aim to save all un necessary waste of fuel or energy required in operating the machinery, whatever the class of work and in whatever department of the work such waste may occur.
There are many notable problems of a more specific nature than the one just named which absorb the attention of mechanical engineers and await their solution. One of these is the reduction in cost of steam power. Owing to the great amount of heat which passes to waste through -the--escape of exhaust steam to •the atmosphere or to the condenser, amounting in the most economical engines to some three fourths of that required in the original genera tion of the steam, there is a wide field for im provement in steam engine economy. Efforts have been made to reduce this waste by employ ing a part of the heat thus lost for evaporating some other liquid having a sufficiently low tem perature of evaporation, and using the vapor thus formed to generate power in an auxiliary cylinder, thereby adding to the total power de veloped by the engine, and reducing in a corre sponding degree the cost of the power per horse power. Another problem of the same kind is the substitution of some other motive power for the steam plant with the object of reducinc its cost. Ga., oil and other forms of internal combustion engines are being widely developed for this purpose. In the conversion of coal into gas by the employment of a gas producer, i and the subsequent use of the gas in the cylinder for developing power, the cost has already been reduced below that of steam power, and even better results may be expected.
The development of the steam ,turbine and its substitution for reciprocating engines is one of the recent problems which mechanical engi neers have worked out with most efficient re sults. One of the most notable features in this
work has been the enormous capacity of single units which have been installed in electric power plants, which would be practically im possible if reciprocating engines were used.
Another problem of mechanical engineering which is important to all business interests is that of rapid transportation by railroad. The great increase in speed on street car lines which has been produced by the adoption of electric ity for driving power and the results obtained by the introduction of electric locomotives for hauling trains on certain railroads of consider able length are familiar to every one. The success already obtained makes it.seem probable that the further adaptation of electricity in railroad work, not only on short lines, but on trunk lines, will meet all the requirements.
The great problem of aerial navigation, which naturally lies in the domain of mechanical engineering, seems in a fair way to be solved. Aeroplanes of sufficient power to carry the operator and one or two passengers are in suc cessful use by expert aviators, and long flights are made with aeroplane in the air a number of hours at a stretch. The utility of the aero plane in connection with operations of war has been demonstrated beyond question, and gov ernment provision of aeroplane fleets has be come a recognized necessity the same as that of armies and navies. That nart of the problem which remains to be solved is the adaptation of the aeroplane, and of the airship as well, to the transportation of passengers and freight on a commercial scale and in such a manner as to be safe and reliable, whatever the condition of air currents or state of weather.
There are other great problems of mechan ical engineering, yet unsolved, which relate to the production of power by the employment of the forces of nature not heretofore utilized. One of these has for its object the utilization of the sun's heat. It has been worked out in a small way in California. A concave mirror having 1,000 square feet of surface has been employed for converging the rays of the sun upon a steam boiler which lies at its focus, and suitable mechanism is arranged for keeping the mirror always turned in the proper direction toward the sun. It is said that in full sunshine this apparatus has developed 10 hol se power. Wind power is widely and em ployed on a small scale, but there remains the problem of overcoming its variable nature by providing means fur it, and of applying the power thus obtained without limitations. The development of tidal power, like that of wind power, is largely a problem of the storage of energy, and no success in this field has been realized.