Pennsylvania Railroad Company. Office of Assistant Chief Engineer, Signals.

The post of Engineer of Signals was created on June 11, 1883, with the appointment of H. F. Cox. This move reflected the growing significance of automatic and semi-automatic signals in promoting safe operations.

On August 1, 1887, George D. Fowle succeeded Cox as Engineer of Signals. He held the position for twenty years, during which time the first generation of electric signals was completed. Fowle was in turn succeeded by Alexander Holley Rudd, who served for thirty years, the name of the office being changed to signal engineer in 1913. Rudd was acknowledged as a signal expert throughout the industry. In 1915, the company developed its distinctive position-light signal in which rows of yellow lights could show a vertical line for clear, a horizontal line for stop, and a 45-degree angle for caution.

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