Cash and Carry

During the London Gin Craze of the early 18th century, when the British government started running sting operations on petty gin sellers, someone invented a device called the “Puss-and-Mew” so that the buyer couldn’t identify the seller in court:

The old Observation, that the English, though no great Inventors themselves, are the best Improvers of other Peoples Inventions, is verified by a fresh Example, in the Parish of St. Giles’s in the Fields, and in other Parts of the Town; where several Shopkeepers, Dealers in Spirituous Liquors, observing the Wonders perform’d by the Figures of the Druggist and the Blackmoor pouring out Wine, have turn’d them to their own great Profit. The Way is this, the Buyer comes into the Entry and cries Puss, and is immediately answer’d by a Voice from within, Mew. A Drawer is then thrust out, into which the Buyer puts his Money, which when drawn back, is soon after thrust out again, with the Quantity of Gin requir’d; the Matter of this new Improvement in Mechanicks, remaining all the while unseen; whereby all Informations are defeated, and the Penalty of the Gin Act evaded.

This is sometimes called the first vending machine.

(From Read’s Weekly Journal, Feb. 18, 1738. Thanks, Nick.)

Worth a Try
Image: Wikipedia

The gravestone of John Renie, a 19th-century house painter, at St. Mary’s Priory Church in Monmouth, Wales, is a 285-letter acrostic puzzle — from the central H the sentence “Here lies John Renie” can be traced out (in king’s moves) in 45,760 different ways. Renie probably carved it himself; according to cleric Lionel Fanthorpe, he hoped it would occupy the devil while he escaped to heaven.

See “Remarkable Inscription” and A Puzzling Exit.

Who’s Calling?

Actual names found by Joseph F. Wilkinson on a CD-ROM of U.S. residential telephone directories, 1996:

Barbara Seville
Gloria Monday
Rosetta Stone
Robin Banks
Frank Earnest
Clark Barr
Frank N. Stein
Georgia Peach
M.T. Head
Minnie Vann
Pearl Harper
Sunny Day
Phil Harmonic
Lance Boyle
King Fisher
Al Dente
Albert Fresco
James Dandy
Laurel Hardy
Nosmo King

A few become distinctive when the last name is listed first:

Cracker, Jack
Dollar, Bill
Wise, Guy
Sweet, Lorraine
North, Carolina
Oopsy, Daisy

“All these memorable names left me with the feeling that my own is quite forgettable,” Wilkinson wrote. “If only my parents had named me Sword, my phone book listing might have really given me an edge.”

(Joseph F. Wilkinson, “What’s in a Name? Just Ask King Fisher, Robin Banks and Minnie Vann,” Smithsonian 26:12 [March 1996], 136.)

Hidden Mothers

In the 19th century, photographic subjects had to hold still during an exposure of 30 seconds or more. That’s hard enough for an adult, but it’s practically impossible for an infant. So mothers would sometimes hide in the scene, impersonating a chair or a pair of curtains, in order to hold the baby still while the photographer did his work:

More in this Flickr group.

Planet Packing

What’s the shortest string of letters that contains the words ONE, TWO, and THREE, each spelled out in order but not necessarily using adjacent letters? It can be done in eight letters — THRWONEE is one example — and it turns out that no shorter solution is possible.

In 2001, A. Ross Eckler set out to do the same thing with the names of the planets, from MERCURY through PLUTO. He got down as far as 26 letters, MNVESARCPJLUPITHOURYANUSER, and to my knowledge no one has found a shorter solution.

Dana Richards offered a discussion of the problem from a computing perspective later that year. He found that Eckler’s task is related to a problem in Garey and Johnson’s 1979 Computers and Intractability.

“Why would planet packing be found in a serious computer science book?” he writes. “It turns out to be an important problem with applications to data compression, DNA sequencing, and job scheduling. … The first practical thing is to abandon all hope of solving the problem with a fast algorithm that always gets the optimal answer.”

(A. Ross Eckler, “Planet Packing,” Word Ways 34:2 [May 2001], 157.)

09/23/2017 UPDATE: Reader Mikko Ratala has found a 25-letter solution: JVSMEURANEPLICTUERNTYESOH. “The string is not unique solution as you can, for example, change the order of the first four letters as you wish.”

Taxicab Geometry

What’s the shortest distance between the points in the lower left and upper right? In our familiar Euclidean geometry, it’s the green line. But in taxicab geometry, an intriguing variant devised by Hermann Minkowski in the 19th century, distance is reckoned as the sum of the absolute differences of Cartesian coordinates — basically the distance that a taxicab would drive if this were a city grid. In that case, the shortest distance between the two points is 12, and it’s shown equally well by the red, blue, and yellow lines. Any of these routes will cover the same “distance” in taking you from one point to the other.

This way of considering things is intriguing in the abstract, but it has some practical value as well. “Taxicab geometry is a more useful model of urban geography than is Euclidean geometry,” writes Eugene F. Krause in Taxicab Geometry. “Only a pigeon would benefit from the knowledge that the Euclidean distance from the Post Office to the Museum [below] is  \sqrt{8} blocks while the Euclidean distance from the Post Office to the City Hall is  \sqrt{9}=3 blocks. This information is worse than useless for a person who is constrained to travel along streets or sidewalks. For people, taxicab distance is the ‘real’ distance. It is not true, for people, that the Museum is ‘closer’ to the Post Office than the City Hall is. In fact, just the opposite is true.”


To earn some money during college, Raymond Smullyan applied for a job as a salesman. He had to take an examination, and one of the questions asked whether he had any objection to telling a small lie now and then. Smullyan did object, but he was afraid that he wouldn’t get the job if he said so. So he lied and said no.

“Later on, I realized I was in a kind of paradox!” Smullyan wrote later. “Did I object to the lie I told the sales company? I realized that I did not! Then since I didn’t object to that particular lie, it therefore followed that I don’t object to all lies, hence my answer ‘No’ was not a lie, but the truth! So was I lying or not?”

(From his book A Mixed Bag, 2016.)

Hot and Cold

The vortex tube is a bit of a magic trick: When a stream of compressed gas is injected into the chamber, it accelerates to a high rate of rotation and moves toward the nozzle on the right. Because of the nozzle’s shape, though, only the quickly rotating outer shell of this gas can escape; the rest moves back through the center of the vortex and escapes through the opening on the left.

The result, perplexingly, is that even though the tube has no moving parts, it emits hot air (up to 200°C) on the right and cold air (down to -50° C) on the left.

Could this principle be used to air-condition a home or vehicle? “That’s what everyone thinks when they first hear about it,” engineer Leslie Inglis told Popular Science in 1976. “I always tell them that they wouldn’t buy a toaster for the kitchen if they had to buy the generator to produce the electricity. You’ve got to think of this as a compressed-air appliance.”

Podcast Episode 169: John Harrison and the Problem of Longitude

john harrison

Ships need a reliable way to know their exact location at sea — and for centuries, the lack of a dependable method caused shipwrecks and economic havoc for every seafaring nation. In this week’s episode of the Futility Closet podcast we’ll meet John Harrison, the self-taught English clockmaker who dedicated his life to crafting a reliable solution to this crucial problem.

We’ll also admire a dentist and puzzle over a magic bus stop.

See full show notes …