Harvard Psychological Studies, Volume 2

by Unknown

In view of the prime importance of electricity to a modern psychological laboratory, a rather elaborate system of wiring has been designed and built in. The unit of this system is a small delivery-board six inches wide by eight inches high, which carries the following five circuits: a, a time-circuit for running magnetic signals; bb, two low-tension circuits for chronoscope, bells, signals, etc.; c, a high-tension alternating current (110 v. and 60 phases) for alt. current motors, to be used where great constancy of speed is desired; d, a high-tension direct current (110 v.) for dir. current motors, where it is desired to vary the speed continuously (by the introduction of resistance). Two such delivery-boards have been set on opposite walls of all except the smallest rooms, which have but one board. Circuits a and b are represented on the board by binding-posts, while the high-tension currents, c and d, appear as flush, protected sockets that take a double-pole plug.

Circuit a is a single circuit led from a time-pendulum permanently set in the battery-room, and carried once around the laboratory. It is connected with the a binding-posts of the individual delivery-boards in parallel. It follows that the time-circuit is alike for all the rooms at any one time; but in different hours the pendulum can be adjusted to give various impulse-rates. If an investigation requires some special rate of impulse, the special time-apparatus is set up in the investigator's room and current for it taken from one of the b pairs of posts.

Each b pair goes directly from the delivery-board to the battery-room and ends at a double-pole (telephone type) socket on a large switch-board. Thus every room has two or four direct and independent connections with the battery-room.

The c and d circuits do not come from the battery-room, but from their respective generators that are stationed outside of the building. They are of course connected at the delivery-boards in parallel.

The large switch-board in the battery-room consists of an upper and a lower part. The upper part bears the double-pole sockets from the b posts in all the rooms; the lower part carries some fifty pairs of single-pole sockets that are connected with the batteries stationed near by. These pairs are labelled, and some give a current from cells of the Leclanché type, others of a gravity type. The student has merely to choose the kind and number of cells that he needs, from the lower part, and connect them with one of the double-pole sockets of the upper part which runs to a b pair in his own room. By connecting two double-pole sockets with each other, the student can establish a circuit between any two rooms of the laboratory,—this for purposes of telephonic or other communication. Since every room has two, and most of the rooms have four of the b circuits, the greatest variety and elasticity of service is attained.

The large switch-board further carries a voltmetre and an ammetre, both of the Weston make, which are reached (electrically) from double-pole jacks (sockets) on the upper part of the board. Thus before connecting the current with his room, the student can in a moment measure its amount and intensity. These instruments are of the flushface type, and dead-beat.

All of the rooms are lighted by electricity, and the lighting system is independent of the delivery-boards. Nine of the rooms are provided with soapstone sinks, and six (not including the lavatories and service-room) with enamelled iron or porcelain sinks. All the sinks have two taps and each of these ends with a screw-thread so as to take a tip and rubber hose. The soapstone sinks were specially designed with soapstone drip-boards. This is probably the best material for a research-room, and the porcelain and enamel sinks were put only where a neater appearance was desired, or where chemicals were to be frequently used—as for instance in the battery and photographic rooms. Gas is not used for illumination, but six rooms are provided with jets for the smoking of drums, soldering, brazing, etc.

The instrument-room is equipped with large dust-proof cases for holding the more delicate and valuable instruments. The larger unused pieces are stored, out of sight but readily accessible, in an attic which has a clear floor-space of something more than half the total area of the laboratory. Dust-proof cases for demonstration and class-work material are provided in the lecture- and class-rooms.

The shop contains a wood-working bench with two vices, tool-racks, shelves, drawers, cupboards, and stock-racks, for the use of students; and a 9-in. lathe, circular saw, grinding- and buffing-machine, separate bench, vice, racks, and drawers for the use of the mechanic. The machinery is run by a 5 h.p. electric motor suspended from one of the outside brick walls, on brackets. One who selects the equipment of such a shop has to weigh carefully the respective merits of circular and band saws; the latter undoubtedly lends itself to a greater variety of uses, but it is also a far more dangerous machine to have running in a room to which students are to be given access. This latter consideration determined in the present case the choice of a circular saw. It is quite dangerous enough, and may be used only by, or under the supervision of, the mechanic.

It has been stated on competent authority that a truly sound-proof room cannot be built except under ground. This has not been attempted, but the laboratory contains one room (no. 17) which is virtually sound-proof. A double door separates it from the adjoining experimenter's room, and double doors also separate this from the main hall. The wall between these two rooms consists of two layers of plaster with special deadening material inserted between. Two small tubes, ordinarily stuffed with felt, connect these rooms. When the acoustical stimulus is a tuning-fork, it is placed in a distant room, connected with one of the b circuits of the sound-proof room, and then with a telephone receiver near the subject's ear.