The Progress of the Century

by Unknown

MECHANICAL ENGINEERING

This is employed in all dynamical engineering. It covers the designs of prime motors of all sorts, steam, gas, and gasoline reciprocating engines; also steam and water turbines, wind-mills, and wave-motors.

It comprises all means of transmitting power, as by shafting, ropes, pneumatic pressure, and compressed air, all of which seem likely to be superseded by electricity.

It covers the construction of machine tools and machinery of all kinds. It enters into all the processes of structural, hydraulic, electrical, and industrial engineering. The special improvements are: The almost universal use of rotary motion, and of the reduplication of parts.

The steam-engine is a machine of reciprocating, converted into rotary, motion by the crank. The progress of mechanical engineering during the nineteenth century is measured by the improvements of the steam-engine, principally in the direction of saving fuel, by the invention of internal combustion or gas-engines, the application of electrical transmission, and, latest, the practical development of steam turbines by Parsons, Westinghouse, Delaval, Curtis, and others. In these a jet of steam impinges upon buckets set upon the circumference of a wheel. It was clearly indicated by the Italian engineer Bronca, in 1629, but he was too early. The time was not ripe, and there were then no machine tools giving the perfection of workmanship required.

Their advantages are that their motion is rotary and not reciprocal. They can develop speed of from 5000 to 30,000 revolutions per minute, while the highest ever attained by a reciprocating engine is not over 1000. Their thermodynamic losses are less, hence they consume less steam and less fuel.

It is a very interesting fact that the basic invention upon which not only steam turbines and electric dynamos, but, indeed, all other parts of mechanical engineering, depend, is of such remote antiquity that we know nothing of its origin. This is the wheel which Gladstone said was the greatest of man’s mechanical inventions, as there is nothing in nature to suggest it.

Duplication of parts has lowered the cost of all products. Clothing is one of these. The parts of ready-made garments and shoes are now cut into shape in numbers at a time, by sharp-edged templates, and then fastened together by sewing-machines.

Mechanical engineering is a good example of the survival of the fittest. Millions of dollars are expended on machinery, when suddenly a new discovery or invention casts them all into the scrap heap, to be replaced by those of greater earning capacity.

Prime motors derive their energy either from coal or other combinations of carbon, such as petroleum, or from gravity. This may come from falling water, and the old-fashioned water-wheels of the eighteenth century were superseded in the nineteenth by turbines, first invented in France and since greatly perfected. These are used in the electrical transmission of water-power at Niagara of 5000 horse-power, and form a very important part of the plant.

The other gravity motors are wind-mills and wave-motors. Wind-mills are an old invention, but have been greatly improved in the United States by the use of the self-reefing wheel. The great plains of the West are subject to sudden, violent gales of wind, and unless the wheel was automatically self-reefing it would often be destroyed. Little has been written about these wheels, but their use is very widely extended, and they perform a most useful function in industrial engineering.

There have been vast numbers of patents taken out for wave-motors. One was invented in Chili, South America, which furnished a constant power for four months, and was utilized in sawing planks. The action of waves is more constant on the Pacific coast of America than elsewhere, and some auxiliary power, such as a gasoline engine, which can be quickly started and stopped, must be provided for use during calm days. The prime cost of such a machine need not exceed that of a steam plant, and the cost of operating is much less than that of any fuel-burning engine. The saving of coal is a very important problem. In a wider sense, we may say that the saving of all the great stores which nature has laid up for us during the past, and which have remained almost untouched until the nineteenth century, is the great problem of to-day.

Petroleum and natural gas may disappear. The ores of gold, silver, and platinum will not last forever. Trees will grow, and iron ores seem to be practically inexhaustible. Chemistry has added a new metal in aluminum, which replaces copper for many purposes. One of the greatest problems of the twentieth century is to discover some chemical process for treating iron, by which oxidation will not take place.

Coal, next to grain, is the most important of nature’s gifts; it can be exhausted, or the cost of mining it become so great that it cannot be obtained in the countries where it is most needed; water, wind, and wave power may take its place to a limited extent, and greater use may be made of the waste gases coming from blast or smelter furnaces, but as nearly all energy comes from coal, its use must be economized, and the greatest economy will come from pulverizing coal and using it in the shape of a fine powder. Inventions have been made trying to deliver this powder into the fire-box as fast as made, for it is as explosive as gunpowder, and as dangerous to store or handle. If this can be done, there will be a saving of coal due to perfect and smokeless combustion, as the admission of air can be entirely regulated, the same blast which throws in the powder furnishing oxygen. Some investigators have estimated that the saving of coal will be as great as twenty per cent. This means 100,000,000 tons of coal annually.

Bituminous coal will then be as smokeless as anthracite, and can be burned in locomotives. Cities will be free from the nuisance of wasted coal, which we call soot. This process will be the best kind of mechanical stoking, and will prevent the necessity of opening the doors of fire-boxes. The boiler-rooms of steamships will no longer be “floating hells,” and the firing of large locomotives will become easy.

Another problem of mechanical engineering is to determine whether it will be found more economical to transform the energy of coal, at the mines, into electric current and send it by wire to cities and other places where it is wanted, or to carry the coal by rail and water, as we now do, to such places, and convert it there by the steam or gas engine.

In favor of the first method it can be said that hills of refuse coal now representing locked-up capital can be burned, and the cost of transportation and handling be saved. Electric energy can now transport power in high voltage economically between coal-mines and most large cities.

The second method has the advantage of not depending on one single source of supply, that may break down, but in having the energy stored in coal-pockets near by the place of use, where it can be applied to separate units of power with no fear of failure.

It seems probable that a combination of the two systems will produce the best results. Where power can be sent electrically from the mines for less cost than the coal can be transported, that method will be used.

To prevent stoppage of works, the separate motors and a store of coal, to be used in cases of emergency, will still be needed, just as has been described as necessary to the commercial success of wave-motors.