Also of course cops on foot had no radios and radios in patrol cars > were rare.
Although eventually of course radios did come in. There's an old joke about three gangsters sitting around shooting the bull. The first guy brags 'My Ford can go 120 miles-per-hour!' 'Aw, that's nuthin'!' retorts the second thug. 'My Chevy goes 130!' 'W-e-l-l-l-l yeah,' wisecracks the third one, the joker of the group. 'But now the cops got those Motorolas that go 186,000 miles-per-second!'
cheers,
Henry