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.
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'