6. The additional or local circuit _r_, in combination with the magnet M, wires _l l'_ _k k'_, battery B, and section of rails of a railroad track, for operation, essentially as described. WILLIAM ROBINSON. Witnesses: JOHN ROONEY, VAN WYCK FOSTER. DR. WILLIAM ROBINSON[2] Electrical and Mechanical Engineer Fellow American Institute of Electrical Engineers Graduate of Wesleyan University with Degrees of A.B. and A.M. Post Graduate of Boston University with Degree of Ph.D. [2] Reprinted from a circular published by Dr. Robinson in 1913. Data Notes Originator and patentee (basic patents, 1872) of the Closed Track Circuit System of Automatic Electric Signaling, the basis of practically every automatic electric block signal system in use on railroads today. The following brief description and comments on this Robinson closed track circuit system are from the Third Annual Report of the Block Signal and Train Control Board to the Interstate Commerce Commission, dated November 22, 1910, pages 177 et seq. "The Track Circuit "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_." "Invention of the Rail Circuit "To Mr. William Robinson the Patent Office records concede the honor of having devised the first practical track or 'rail circuit.' This comprised what is termed the _closed_ track circuit in distinction from the _open_ form that preceded it." * * * "Closed track circuits are very reliable, wholly safe in principle, and simple of application and maintenance." * * * "Attention is therefore directed to the closed track circuit--the basis of all modern automatic signal systems that are entitled to recognition as embodying the highest attainments in the matter of safety." "The Closed Track Circuit "The closed track circuit in its simplest form consists of the two rails of a section acting as prime conductors, a generator maintaining a difference of potential between them when the rails are unoccupied, and one or more relays connected across the rails."