A century ago, cops knew Morse Code, as shown by these New York City police officers appearing in the March 1917 issue of Popular Mechanics.

According to the accompanying article, instruction in wireless telegraphy was being given to the officers, and a wireless apparatus had been set up at headquarters. That station worked in conjunction with other stations around the harbor, and also with a number of private wireless stations that had been placed at the service of the police for emergency work.

Motorcycle couriers would carry messages from the wireless stations to district and precinct offices. At press time, the department had eight certified wireless operators, and sixteen more were under instruction.