which the passenger can send the car to any floor. At each 
other landing there is a single button by means of which the 
car, if not in use, can be called to the floor. The well doors 
are of the swinging type and are self-closing. This arrangement 
prevents the holding of the car at a floor because the 
operator forgot to close the gate. These cars can carry 1,500
pounds at 300 feet per minute and serve sixteen landings. 
The winding machines are of the wormier traction type, 
located at the top of the wells. The controllers are designed 
to stop cars accurately level with floors.
       One elevator is provided for carrying members of the 
library staff and others having access to the stack; it runs in 
the stack from the basement to the seventh floor mezzanine, 
serving sixteen landings. This elevator has full automatic 
push button control, but differs from that of the two book 
elevators.
       There is a group of buttons in the car to send it to any 
landing. At each landing there are two buttons, one marked 
"up" and one marked "down." Either button will call the 
car to the floor if it is not in use, but a waiting passenger is 
expected to push the button corresponding to the direction 
in which he wishes to go. If the car has already been started 
and is moving in the direction the prospective passenger 
wishes to go, and if it is approaching the landing at which 
he waits, then the car will stop and allow the passenger to 
enter. The new passenger pushes the proper button for the 
floor at which he is to leave, and the car proceeds. Several 
stops of this kind may be made, and the car will continue in 
the same direction making stops according as the buttons in 
the car have been pushed, until all passengers who have 
entered the car have reached their destination. The operation 
of all other buttons will have no effect on the car movement 
until the last passenger has reached his floor. This type of 
control is known as "collective" control and is valuable for 
elevators having a high rise.
       This staff elevator has the swinging type of well doors