has provided a switchboard through which any outlet may 
be connected to any other outlet in the building, or to the 
outside system.
       There is a clock system consisting of a master clock, 
secondary clocks, time stamps, an employees' time recorder, and 
bells for giving warning of the closing time of the library. 
This system is operated from a storage battery which is kept 
charged automatically.
       On account of the large area of the bookstack, signal 
lamps in groups of three have been installed at several places 
in the aisles on each floor. The location of these lamps was 
so chosen that the attendant can see one or more of the groups 
from any point in the main aisles. The lamps indicate the 
arrival at the floor of one or both dumb-waiters, one or both 
elevators, or a carrier with call slips via the pneumatic tube.

ELEVATORS

       The building is provided with six elevators and two 
dumb-waiters, all driven by electric motors. This apparatus 
is of the most modern design and construction. 
       Two of the elevators carry operators and are used by 
passengers to the special collections and seminar rooms; 
they run from the basement to the seventh floor and can carry 
2,500 pounds at 450 feet per minute. The winding machines 
are of the gearless traction type. The car gates and well 
doors are hand operated, and the well doors have door 
closers. The system of control is that known as unit 
multivoltage control with hand operated switches in the cars 
which give smooth and quiet operation.
       Two of the elevators are used principally for returning 
books to the shelves. These elevators have full automatic 
push button control; there is a group of buttons outside the 
well at the first floor for each car by means of which the car 
can be called to that floor from any point in the well, if not 
in use, and can be sent from the first floor to any other floor. 
There is a similar group of buttons in the car by means of