The Flettner Rotor

https://commons.wikimedia.org/wiki/File:Buckau_Flettner_Rotor_Ship_LOC_37764u.jpg

Canvas sails had been used for thousands of years when German engineer Anton Flettner realized that rotating cylinders might work as well: The spin produces a difference in pressure on opposite sides of the cylinder, and this can propel a ship through the water.

The idea made a splash when it was introduced in the 1920s, and an experimental vessel crossed the Atlantic in 1926, but the rotating drums consumed a discouraging amount of power and Flettner moved on to other projects. The principle has been revived lately, though, in hopes of increasing the fuel efficiency of conventionally powered ships.

More Bad Verse

For years I’ve been hearing about an immortally bad volume of poetry, The Captain of the ‘Dolphin’ and Other Poems of the Sea, by Frederick J. Johnston-Smith. The glimpses I’ve seen look fantastic:

We piled more wood upon the blazing hearth —
More broken planks from off the mould’ring wreck;
The billets, all composed of Norway pine,
Were evidently portions of the deck.

The morning came the tempest’s trail impatient to elute;
The merry birds assistance gave — played each his fife or flute.

A balminess the darkened hours had brought from out the south.
Each breaker doffed its cap of white and shut its blatant mouth.

Strike, strike your flag, Sidonia,
And lessen death and pain!
“Strike!” “Fight!” are but synonyma
For misery to Spain.

(Where the Goddess Aurora sits shaking her fan
In the face of a vapourless moon —
Where the sun circles round for the half of the year
And is cold — like a yellow balloon)

(to a lapwing:)

I thank you for cutting the thread of my thought
With a snip of your scissors-like bill,
For why should my mind with a thinking be fraught
Of men’s indefectible ill?

I’ve just discovered that the whole thing is on the Internet Archive — including a Glossary of Nautical Terms in which the poet informs us that the “wheel” is “that with which the helmsman steers the ship.”

Prime Circles

Is it always possible to arrange the numbers from 1 to 2n in a circle so that each adjacent pair sums to a prime?

  4  1
7      2
6      3
  5  8

As of 2016, solutions have been found for every case up to n = 106 — but no one has yet proven that it’s always possible.

Podcast Episode 326: The Recluse of Herald Square

ida wood

In 1931, a 93-year-old widow was discovered to be hoarding great wealth in New York’s Herald Square Hotel. Her death touched off an inquiry that revealed a glittering past — and a great secret. In this week’s episode of the Futility Closet podcast, we’ll tell the story of Ida Wood, which has been called “one of the most sensational inheritance cases in American history.”

We’ll also revisit the Candy Bomber and puzzle over some excessive travel.

See full show notes …

Technique

MIT astrophysicist Walter Lewin became renowned for his ability to draw dotted lines on a blackboard.

“The idea is that the chalk should not be too short,” he explained. “You have to push on the board, and if you don’t push too hard, it will jump. If you go a little faster, then you’re in business.”

He explains it further below:

Wave

The world’s largest anamorphic illusion is this startling display in Seoul’s Gangnam District. Measuring 80 meters by 20, it runs for 18 hours a day, the creation of design firm d’strict.

Below is another project by the same creators: the “infinity wall” in the lobby of Nexen Tire’s Central Research Institute, also in Seoul.

Background

https://commons.wikimedia.org/wiki/File:FDR_conference_1944_HD-SN-99-02408.JPEG

An avid stamp collector in earlier life, Franklin Roosevelt brought a surprisingly detailed knowledge of remote regions to his role as commander-in-chief.

“The president’s knowledge of world geography was amazing,” wrote his naval aide, John McCrea. “I once remarked about this, and he replied, ‘If a stamp collector really studies his stamps, he can pick up a great deal of information.'”

(From McCrea’s 2016 memoir, Captain McCrea’s War.)

Decorum

https://commons.wikimedia.org/wiki/File:Bernard_Law_Montgomery.jpg

We were all used to the heat; but whereas the desert was dry, Sicily was humid. … I well remember an incident that occurred one day as I was driving in my open car up to the front. I saw a lorry coming towards me with a soldier apparently completely naked in the driver’s seat, wearing a silk top hat. As the lorry passed me, the driver leant out from his cab and took off his hat to me with a sweeping and gallant gesture. I just roared with laughter. However, while I was not particular about dress so long as the soldiers fought well and we won our battles, I at once decided that there were limits. When I got back to my headquarters I issued the only order I ever issued about dress in the Eighth Army; it read as follows: ‘Top hats will not be worn in the Eighth Army.’

The Memoirs of Field Marshal Montgomery, 1958

Correspondence

A problem from the Sixth International Mathematical Olympiad, 1964: Seventeen people correspond by mail, each with all the rest. They discuss only three topics, and each pair of correspondents addresses only one of these. Prove that there are at least three people who write to each other about the same topic.

Click for Answer