Show safety elevators an improved system has been adopted in id respect to the new elevators for the library of congress they are built with a special view to safety and in addition to a safety catch are provided with what is termed the air cushion the latter not a real cushion inasmuch as it is not sc soft nor is it made and put in position being formed only when the elevator is dropped to the bottom of the shaft and thus all wear and tear on the i 1 cushion is avoided the principle is very simple at the bottom of the th e shaft is a well about 13 feet in depth the sides of which are so arranged as to come at the top within the sixteenth of an inch of the side bide of the elevator this apace gradually growing larger until there is a distance of an inch and a half between the elevator and the shaft when the elevator is ia dropped from the roof it pushes before it lt a quantity of air air and dropping into the well the air IS ia compressed and escaping very slowly allows the elevator to settle easily |