The dynamo laboratory at the north end of the basement contains about twenty machines, all the generators being motor driven either directly or through shafting. Of considerable historical interest are the two Sprague railway motors, shown in the cut on the right under the heating chambers. They are the first pair of motors operated under a car by the West End Street Railway Company of Boston. Another interesting machine is a twenty-four pole Mordey alternator mounted on the same bedplate with and directly connected to a 125 volt direct current motor. This alternator yields currents of any frequency up to about twelve hundred periods per second and its forty-eight armature coils are arranged in twelve independent circuits, thus admitting of a great range of voltage and current in the output of the machine at normal field excitation. This and many other machines in this room have been designed and constructed in the college workshops and represent the theses of graduating students. Superintendent Raymond of the General Electric Co., has said that most of them are "commercial machines" that is, good enough to put on the market. In the view of the dynamo room the immediate foreground shows a pair of machines that can be used as direct current generators or motors, as alternating generators or synchronous motors of one, two, three, four or six phases, and as synchronous convertors. These also are the product of our workshops, and with them a great variety of important tests can be made.

W. L. H.