The Flettner Rotor

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.


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:


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.

Moving Parts
Image: Wikimedia Commons

The Henry Ford museum in Dearborn, Mich., contains an “exploded” 1924 Model T touring car, its parts arrayed in the order of their assembly, echoing the component diagrams in the vehicle’s manuals.

Ford’s assembly line was inspired by the “disassembly line” that engineer William Klann observed in a Chicago slaughterhouse, in which one worker at a conveyor belt performed the same task repeatedly without himself moving. Ford’s line divided his car’s assembly into 45 steps, producing each unit in 93 minutes.

Boom Town

In 1757 Ben Franklin revealed “How to make a Striking Sundial, by which not only a Man’s own Family, but all his Neighbours for ten Miles round, may know what o’Clock it is, when the Sun shines, without seeing the Dial”:

Chuse an open Place in your Yard or Garden, on which the Sun may shine all Day without any Impediment from Trees or Buildings. On the Ground mark out your Hour Lines, as for a horizontal Dial, according to Art, taking Room enough for the Guns. On the Line for One o’Clock, place one Gun; on the Two o’Clock Line two Guns, and so of the rest. The Guns must all be charged with Powder, but Ball is unnecessary. Your Gnomon or Style must have twelve burning Glasses annex’d to it, and be so placed as that the Sun shining through the Glasses, one after the other, shall cause the Focus or burning Spot to fall on the Hour Line of One for Example, at one a Clock, and there kindle a Train of Gunpowder that shall fire one Gun. At Two a Clock, a Focus shall fall on the Hour Line of Two, and kindle another Train that shall discharge two Guns successively; and so of the rest.

Note, There must be 78 Guns in all. Thirty-two Pounders will be best for this Use; but 18 Pounders may do, and will cost less, as well as use less Powder, for nine Pounds of Powder will do for one Charge of each eighteen Pounder, whereas the Thirty-two Pounders would require for each Gun 16 Pounds.

Note also, That the chief Expence will be the Powder, for the Cannon once bought, will, with Care, last 100 Years.

Note moreover, That there will be a great Saving of Powder in cloudy Days.

(From Poor Richard Improved. He was mocking a class of overambitious amateur experimenters called virtuosi. “Kind Reader, Methinks I hear thee say, That it is indeed a good Thing to know how the Time passes, but this Kind of Dial, notwithstanding the mentioned Savings, would be very expensive; and the Cost greater than the Advantage. Thou art wise, my Friend, to be so considerate beforehand; some Fools would not have found out so much, till they had made the Dial and try’d it. Let all such learn that many a private and many a publick Project, are like this Striking Dial, great Cost for little Profit.”)

The Final Frontier

The original Star Trek was presented in the rather boxy aspect ratio of 1960s television. Now San Francisco illustrator Nick Acosta has stitched together screenshots to see how it would have appeared in a widescreen format:

I created this project of what the show would have looked like in Cinerama widescreen. As a kid the show always felt bigger and more epic than it appears to me as an adult. I was able to create these shots by waiting for the camera to pan and then I stitched the separate shots together. The result is pretty epic. It reminds me of the classic science fiction movies of the 50’s and 60’s. Suddenly the show has a ‘Forbidden Planet’ vibe. Other shots remind me of how director Robert Wise would use a camera technique to keep the foreground and background elements in focus.

More at his website. (Via Cliff Pickover.)

Brave New World

Only a few years back those who carried Umbrellas were held to be legitimate butts. They were old fogies, careful of their health, and so on; but now-a-days we are wiser. Everybody has his Umbrella. It is both cheaper and better made than of old; who, then, so poor he cannot afford one? To see a man going out in the rain umbrella-less excites as much mirth as ever did the sight of those who first — wiser than their generation — availed themselves of this now universal shelter.

— William Sangster, Umbrellas and Their History, 1855

In 1899 Notes & Queries reprinted an account, now thought to be apocryphal, of “the first silk hat in London”:

It was in evidence that Mr. Hetherington, who is well connected, appeared upon the public highway wearing upon his head what he called a silk hat (which was offered in evidence), a tall structure, having a shiny lustre, and calculated to frighten timid people. As a matter of fact, the officers of the Crown stated that several women fainted at the unusual sight, while children screamed, dogs yelped, and a young son of Cordwainer Thomas, who was returning from a chandler’s shop, was thrown down by the crowd which had collected and had his right arm broken.

Supposedly Hetherington argued that he’d broken no law, and the Times backed him up: “In these days of enlightenment it must be considered an advance in dress reform, and one which is bound, sooner or later, to stamp its character upon the entire community.”

The Tunnel of Eupalinos

When the Greek engineer Eupalinos contrived a tunnel in the 6th century B.C. to carry water through Mount Kastro to Samos, he started digging simultaneously from the north and south, hoping that the two tunnels would meet in the heart of the mountain. He arranged this through some timely doglegs: When the two teams could hear one another (meaning they were about 12 meters apart), each deviated from its course in both the horizontal (left) and vertical (right) planes:
Images: Wikimedia Commons

This ensured that they wouldn’t tunnel on hopelessly past one another on parallel courses.

This worked amazingly well: In fact the vertical alignment, established using levels at the start, had been maintained so faithfully that the two tunnels differed by only a few millimeters, though they’d traversed a combined distance of more than a thousand meters.

This is only the second known tunnel to be excavated successfully simultaneously from both ends, and the first to accomplish this feat using geometric principles, which Euclid would codify only centuries later.