The Hot Sheet

Communications: Murphy Call Box

By CPHS / 01 May 2020

In 1907, Jerry Murphy developed his most efficient and successful version of the call box system.  The new call boxes were significantly smaller – still tall, but made of steel…

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Criminal Identification: Fingerprinting

By CPHS / 25 April 2020

In 1904, George Koestle and Chief of Police Fred Kohler traveled to the St. Louis World’s Fair to witness a demonstration of a new method of criminal identification, fingerprinting.  Based…

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Early Electric Traffic Signals

By CPHS / 21 April 2020

Many more attempts at designing a functional traffic signal followed. In 1916, Clevelanders John Tomko, CW Oppenlander and SW Oppenlander invented an “electric semaphore” for “minimizing traffic hazards.” The device…

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