Twelve seconds, and then three more.

The number people remember from 17 December 1903 is twelve seconds, which sounds like a round figure invented for a plaque. It is not. It is the duration of the first successful powered, controlled, heavier-than-air flight, measured on the sand at Kill Devil Hills, North Carolina, from a sixty-foot wooden rail, with Orville Wright prone on the lower wing and Wilbur running at the tip.

At 10:35 in the morning the wind was about twenty-seven miles an hour, harder than they wanted. The machine’s predicted cruising speed was only about thirty to thirty-five. A headwind that strong turns progress over the ground into a crawl. The first flight covered about 120 feet at a groundspeed of about 6.8 miles an hour and an airspeed of about 34. From the dunes it would have looked almost still. In the air it was doing the work. John T. Daniels of the nearby lifesaving station tripped a camera already aimed at the empty space in front of the rail, and the plate shows the machine off the sand with Wilbur in stride. That is the record of those twelve seconds.

What the number does not mean is that they only flew once, or that twelve seconds was the longest they managed. They flew four times that day, taking turns. Wilbur went 175 feet. Orville went 200. Then Wilbur again, 852 feet in 59 seconds, which is the flight a plaque would choose if duration were the point. After that a gust rolled the machine and broke it beyond a field repair, and the season was over. The brothers telegraphed the numbers to their father in Dayton. The first flight is still the first one: powered, heavier than air, and under control, even though the fourth one went farther.

Three days earlier the order had been the other way around. On 14 December they tossed a coin. Wilbur won, left the rail, climbed too steeply, stalled, and hit the sand. The machine was airborne about three and a half seconds. The elevator was damaged, they repaired it, and the 17th became Orville’s turn. That earlier hop is why twelve seconds is not a slogan. It is the first time the machine stayed with the pilot long enough to count as a flight.

The gliders had already taught them how to fly. Powered takeoff asked for a different geometry, because the 1903 machine was too heavy to be launched by hand, which is why the rail is in the story at all. None of this is a quarrel with anyone who learned the short version. Twelve seconds is the correct first number. Fifty-nine seconds is the correct last number of the morning. The ground under both is Kill Devil Hills, not the village of Kitty Hawk four miles north, which had the telegraph and therefore the dateline.

If you want the data on a shirt, the 12 Seconds heavyweight tee is the garment that carries the time, the distance, and the duration. The story lives on the site either way, at departure1903.com.