Are you aware how fast your vehicle was going, sir?

If you have read, over at Paul Collins’s Weekend Stubble, that in 1903 the speed of thirty miles per hour earned a car the epithet “scorcher” in the New York Times, and that the speed limit in Long Branch, New Jersey, was in that year six miles per hour, you may have wondered how, in the time before radar, such laws were enforced.

As it happens, that question was still novel enough in 1926 for Upton Sinclair to put the answer in the opening pages of his novel Oil!. It is 1912, and the hero, Bunny Ross, age thirteen, is being driven through southern California by his father, who is going fifty miles per hour in a thirty-mile-per-hour zone. Suddenly they fall into “A speed-trap!”:

Oho! An adventure to make a boy’s heart jump! . . . It must be a dreadful thing to be a “speed-cop”, and have the whole human race for your enemy! To stoop to disreputable actions—hiding yourself in bushes, holding a stop-watch in hand, and with a confederate at a certain measured distance down the road, also holding a stop-watch, and with a telephone line connecting the two of them, so they could keep tab on motorists who passed! They had even invented a device of mirrors, which could be set up by the roadside, so that one man could get the flash of a car as it passed, and keep the time. This was a trouble the motorist had to keep incessant watch for; at the slightest sign of anything suspicious, he must slow up quickly—and yet not too quickly—no, just a natural slowing, such as any man would employ if he should discover that he had accidentally, for the briefest moment, exceeded ever so slightly the limits of complete safety in driving.

The technology of speed traps may have changed, but it seems that the psychology of the driver suddenly aware that he is under surveillance is one of the eternal and unchanging verities of the universe.