Two Sheffield engineers introduced this brainstorm in 1939 — when a motorist realizes he’s about to hit a pedestrian he can pull an emergency lever and the bumper deploys a life-saving “scoop.”

A similar device had appeared in Berlin in 1927 (below). I don’t know whether either was put to practical use.

In 1971, two aeronautical engineering students set out to make an aircraft by mating the wings, engine, and airframe of a Cessna Skymaster to a modified Ford Pinto. In principle you could drive to the airport, attach the wings in two minutes, and get quickly into the air under the combined power of two engines. At your destination you’d land, stop quickly using the car’s four-wheel brakes, detach the wings, and drive off.

By 1973, two prototypes had been built and the FAA was considering certification, but on two testing flights a wing strut detached from the car. One pilot had to land in a bean field, and another died when the wing folded. The project was dropped.

Suppose you build a ship that can take you to Barnard’s Star. Should you depart today? Perhaps not: Our civilization might create a faster ship tomorrow that will overtake you on the journey. But clearly if you wait too long then you’ll simply lose out to an earlier ship. There must be some optimal waiting time that will deliver you to the star before any other pilot.

What is that time? “It has been shown that taking reasonable estimates for growth, an interstellar journey of 6 light years can best be made in about 635 years from now if growth continues at about 1.4% per annum,” writes researcher Andrew Kennedy. “At this point, the journey could be made in 145 years.”

(Andrew Kennedy, “Interstellar Travel: The Wait Calculation and the Incentive Trap of Progress,” Journal of the British Interplanetary Society 59:7 [2006], 239-246.)

Designed in 1804, the Grand Shaft, at the Western Heights of Dover, is a triple helix, the only such staircase in Britain. As with Vatican City’s Bramante Staircase, this design accommodates a large number of passengers while minimizing interference among them — using it, a large number of troops might quickly descend the 140 feet from the heights to the town below, while others might even ascend at the same time, using a different spiral.

In 1812 a Mr. Leith of Walmer rode his horse up the stair for a bet, and local legend has it that during Victorian times the separate spirals were assigned to “officers and their ladies,” “sergeants and their wives,” and “soldiers and their women.”

(Thanks, Dave.)

In 2010, as the Colombian government was preparing to rescue 16 soldiers held by armed FARC guerrillas, it looked in vain for a way to alert the soldiers without tipping off their captors. Finally Colonel Jose Espejo arranged to have local radio stations broadcast a pop song that contained a message in Morse code, which the soldiers had learned in basic training but that the guerrillas likely wouldn’t recognize.

The lyrics run, “In the middle of the night / Thinking about what I love the most / I feel the need to sing … About how much I miss them.” And hidden at three points in the song (1:30, 2:30, 3:30), in Morse code, is the message “19 people rescued. You are next. Don’t lose hope.”

“The hostages were listening to our own stations, so we made sure the song was played,” Espejo told The Verge. “The code message said, ‘you’re next’ because the hostages thought if they ran away, they would die in the jungle. We let them know that our troops were nearby.”

It worked. “We know of hostages who heard the message,” Espejo said, “and were able to escape and provide information that led to the release of more hostages.”

Introduced by Eberhard Faber in 1934, the Blackwing 602 premium writing pencil was stamped with the words “Half the Pressure, Twice the Speed”: Compared to an ordinary pencil, its core contained more graphite, less clay, and wax, so that it wrote like a pencil of 4B hardness but with a unique gliding feel.

It has attracted an impressive roster of creative admirers, including Walt Disney, Stephen Sondheim, Quincy Jones, Vladimir Nabokov, and John Steinbeck, who wrote, “I have found a new kind of pencil — the best I have ever had. Of course it costs three times as much too, but it is black and soft but doesn’t break off. I think I will always use these. They are called Blackwings and they really glide over the paper.”

Steinbeck would use a Blackwing pencil right down to the ferrule (pencil devotees now call this “Steinbeck stage”) and then pass them on to his son, another writer. “Writing with a Blackwing 602, more than any other pencil, feels like an event — something like a rite of passage for a pencil obsessive,” writes Caroline Weaver in The Pencil Perfect: The Untold Story of a Cultural Icon (2017). “When they are sold in my shop I always encourage the customer to sharpen it at least once and to use it for special occasions, because most of the pleasure of owning it comes from knowing what it feels like to write with it as much as it comes from the history.”