The Invention of the Track Circuit / The history of Dr. William Robinson's invention of the track circuit, the fundamental unit which made possible our present automatic block signaling and interlocking systems

THE HISTORY OF DR. WILLIAM ROBINSON'S INVENTION OF THE TRACK CIRCUIT
THE FUNDAMENTAL UNIT WHICH MADE POSSIBLE OUR PRESENT AUTOMATIC BLOCK SIGNALING AND INTERLOCKING SYSTEMS
SIGNAL SECTION AMERICAN RAILWAY ASSOCIATION NEW YORK 1922
Believing that no more fitting memorial can be prepared in honor of Dr. William Robinson than to reproduce the salient points relating to his great achievement as written and published by himself in 1906 under the title of History of Automatic Electric and Electrically Controlled Fluid Pressure Signal Systems for Railroads, the committee has accordingly drawn largely from this pamphlet for the material contained in Part I.
Part II is devoted to W. A. Baldwin, formerly General Superintendent of the Pennsylvania Railroad, who was responsible for the first installations of automatic block signals controlled by track circuits.
As this memorial would not be complete without a description of the track circuit, its principle and operation under present day signaling practices, Part III is accordingly devoted to this subject.
HERBERT S. BALLIET, Chairman ; KEITH E. KELLENBERGER, HENRY M. SPERRY, Committee .
Perhaps no single invention in the history of the development of railway transportation has contributed more toward safety and despatch in that field than the track circuit. By this invention, simple in itself, the foundation was obtained for the development of practically every one of the intricate systems of railway block signaling in use today wherein the train is, under all conditions, continuously active in maintaining its own protection.
In other words, the track circuit is today the only medium recognized as fundamentally safe by experts in railway signaling whereby a train or any part thereof may retain continuous and direct control of a block signal while occupying any portion of the track guarded by the signal .
Adopted at Annual Meeting of Signal Section, A.R.A. Chicago, June, 1921
Whereas, Almighty God, in the exercise of His Divine will, has removed from this world our late honorary member, Dr. William Robinson, and,