United States Navy, inventor He was commissioned as an
ensign in the
United States Navy. During his ensuing naval service, he first served on the
USS Richmond, then the
USS Minnesota. While in Asia, Sprague wrote stories he filed for the
Boston Herald. He improved designs for a spring-loaded
trolley pole that had been developed in 1885 by
Charles Van Depoele, devised a greatly improved mounting for streetcar
motors and better gear designs, By January 1889, Boston had its first electric streetcars – which would be the first in the Americas to go underground, some eight years later, as the
Tremont Street Subway – and which had become so popular and noteworthy that poet
Oliver Wendell Holmes composed a verse about the new trolley pole technology, and the sparking contact shoe at its apex: Sprague's system of electric supply was a great advantage in relation to the first bipolar U-tube overhead lines, in everyday use since 1883 on the
Mödling and Hinterbrühl Tram.
Electric elevators While electrifying the streetcars of Richmond, the increased passenger capacity and speed gave Sprague the notion that similar results could be achieved in vertical transportation — electric
elevators. He saw that increasing the capacity of elevator shafts would not only save passengers' time but would also increase the earnings of tall buildings, with height limited by the total floor space taken up in the shaftways by slow hydraulic-powered elevators. In 1892, Sprague founded the Sprague Electric Elevator Company. Working with
Charles R. Pratt he developed the Sprague-Pratt Electric Elevator, the first of which was installed in the
Postal Telegraph Building in 1894. The company developed floor control, automatic elevators, acceleration control of car safeties, and several freight elevators. The Sprague-Pratt
elevator ran faster and with larger loads than hydraulic or steam elevators, and 584 elevators had been installed worldwide. Sprague sold his company to the
Otis Elevator Company in 1895.
Multiple unit train controls Sprague's experience with electric elevators led him to devise a
multiple-unit system of electric railway operation, which accelerated the development of
electric traction. In the multiple-unit system, each car of the train carries electric traction motors. By means of relays energized by train-line wires, the
engineer (or
motorman) commands all of the traction motors in the train to act together. For lighter trains, there is no need for
locomotives, so every car in the train can generate revenue. Where locomotives are used, one person can control all of them. Sprague's first multiple-unit order was from the
South Side Elevated Railroad (the first of several elevated railways locally known as the
"L") in
Chicago, Illinois. This success was quickly followed by substantial multiple-unit contracts in
Brooklyn, New York, and
Boston, Massachusetts.
New York: Grand Central, elevators in skyscrapers From 1896 to 1900 Sprague served on the Commission for Terminal Electrification of the
New York Central Railroad, including the
Grand Central Station in
New York City, where he designed a system of automatic train control to ensure compliance with trackside signals. He founded the Sprague Safety Control & Signal Corporation to develop and build this system. Along with
William J. Wilgus, he designed the Wilgus-Sprague bottom contact
third rail system used by the railroads leading into Grand Central Terminal. During
World War I, Sprague served on the Naval Consulting Board. Then, in the 1920s, he devised a method for safely running two independent elevators, local and express, in a single shaft, to conserve floor space. He sold this system, along with systems for activating elevator car safety systems when acceleration or speed became too great, to the
Westinghouse Company. ==Legacy==