Horizontal Emery Testing Machine of 300,000 Pounds Capacity in the Applied Mechanics Laboratory.
The hydraulic laboratory is well equipped for the study of the laws of flowing water, having a steel tank five feet in diameter and twenty-seven feet high, with a system of stand-pipes eighty-five feet high, reaching to the top of the building. This tank is furnished with gates and other apparatus suitable for experiments on the flow from orifices, and connected with a system of horizontal pipes by which a large variety of other investigations may be carried on. Among the other apparatus of interest may be mentioned two impact water wheels, placed in housings with glass sides so that the action of the water on striking the buckets can be observed.
Some experiments have already been made in the laboratory on the flow of air, the results of which have been communicated by Professor Peabody to the American Society of Mechanical Engineers. It is now intended to continue the study of the flow of air and its use as a motive power in great detail, just as the flow of water is studied, and an air compressor of 100 horse-power, which will produce a pressure of twenty-five hundred pounds, is now being installed.
The 100,000 Pound Beam Machine in the Applied Mechanics Laboratory.
The laboratory for testing the strength of materials was established in 1881 by Prof. G. Lanza, and has since been extensively developed under his direction, until it is now one of the most complete in the world. It is perhaps not too much to say that the experiments made in this laboratory have in some respects revolutionized the ideas of engineers. Previous to its establishment, the only tests of timber that had been made were upon small selected specimens one or two inches square and a few feet long. The results of these tests had been used for years by architects and engineers, and they were given in all the engineering handbooks. In the Institute laboratory there were conducted the first systematic and extended tests of beams of commercial size. The results soon showed that the strength of such timber was a great deal less than previous tests on small beams had indicated, and the practice of engineers and architects has since that time been completely modified through the results obtained in this and similar laboratories. In this way does the work of such a laboratory become of direct and lasting value to the arts. The central piece of apparatus of the Institute laboratory is the Emery machine, similar to the great machine at the Watertown arsenal, with a capacity of three hundred thousand pounds. But in addition to this machine there are a dozen or more other machines designed to test beams, columns, rope, wire and, in fact, materials of every kind and in every form. An interesting machine is that for testing shafts in torsion, and it is instructive to see it twist off with apparent ease a steel shaft three inches in diameter, twisting the fibers before they break till the rod resembles a barber’s pole. There are also beam-testing machines with capacities up to one hundred thousand pounds, in which not only beams but wooden trusses may be tested to the breaking point. Some of the apparatus is of great delicacy; for instance, one instrument will measure the twist of a steel shaft two and a half inches in diameter and six feet long so delicately that the effect of a twist given by one’s hand is distinctly visible; scientifically speaking, it will measure an angle of twist of two seconds. There is also a machine designed for testing stone arches, having a capacity of four hundred thousand pounds and suitable for an investigation of many questions concerning these uncertain structures; also machinery for studying the wear of brake shoes and wheel tires, a subject in regard to which there is room for much investigation. Finally, mention should be made of machinery for investigating the interesting subject of the effect of repetition of stress.
Forge Shop.
The tests performed in the engineering laboratory cover almost the entire range of mechanical science. Sometimes investigations are carried on through a number of years; for instance, during three successive years experiments were conducted and formed the subject of theses on the proper method of counterbalancing the reciprocating parts of a locomotive. Nor are the tests performed by the Institute students as a regular part of their instruction confined to these laboratories, as is made evident by the fifty-hour test of the West End Street Railway power station and the twenty-four hour test of the pumping engine at Chestnut Hill, both recently carried out.
In connection with the engineering laboratories, brief mention may be made of the shops, which form an important adjunct of the laboratories. They consist of a shop for carpentry, wood-turning and pattern-making, equipped with forty carpenters’ benches, thirty-six pattern-makers’ benches and a full equipment of saws, planers, lathes, etc.; a foundry with a cupola furnace for melting iron, thirty-two moulders’ benches, two brass furnaces and a core-oven; a forge shop with thirty-two forges, a power hammer, vises, etc.; a machine shop with about forty lathes, together with drills, planers and all the other necessary apparatus used in machine tool work.