The Halkett Boat

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

Royal Navy officer Peter Halkett designed this lightweight “boat cloak” in 1844. When deflated, its hull could be worn as a cloak, the oar used as a walking stick, and the sail as an umbrella, but a portable bellows could inflate it in four minutes into a craft that could carry eight people.

Explorer John Richardson, who had nearly died of hypothermia trying to cross an arctic river during John Franklin’s disastrous Coppermine Expedition of 1819, wrote that “Had we been possessed of such a contrivance in our first expedition, I have little doubt of our having brought the whole party in safely.” But the navy saw no use for Halkett’s boats, and his efforts to promote them to outdoorsmen similarly failed. The two remaining specimens reside in museums.

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

| Technology

Bootstrap Percolation

grid infection puzzle

On a 12 × 12 grid, some squares are infected and some are healthy. On each turn, a healthy square becomes infected if it has two or more infected orthogonal neighbors. (In the example above, the black squares are infected, the white squares are healthy, and the gray squares will be infected next turn.) What’s the smallest number of initially infected squares that can spread an infection over the whole board?

Click for Answer
| Puzzles

Naturally

Steven Bartlett and Peter Suber’s Self-Reference: Reflections on Reflexivity contains a bibliography of works on reflexivity.

It includes an entry for Steven Bartlett and Peter Suber’s Self-Reference: Reflections on Reflexivity.

| Science & Math

Unquote

http://commons.wikimedia.org/wiki/File:Redrosedust_wright_f2000.jpg

“Whether you can observe a thing or not depends on the theory which you use. It is the theory which decides what can be observed.” — Albert Einstein

“When we observe nature, and especially the ordering of nature, it is always ourselves alone we are observing.” — G.C. Lichtenberg

| Quotations

Counterfeit Redux

A more challenging version of the Counterfeit Coin puzzle from 2011:

You have 12 coins, one of which has been replaced with a counterfeit. The false coin differs in weight from the true ones, but you don’t know whether it’s heavier or lighter. How can find it using three weighings in a pan balance?

Click for Answer
| Puzzles

Moving Images

By turning the traditional rules of perspective inside out, the paintings of British artist Patrick Hughes induce a compelling illusion in three dimensions.

“Reverspectives are three-dimensional paintings that when viewed from the front initially give the impression of viewing a painted flat surface that shows a perspective view,” he writes. “However as soon as the viewer moves their head even slightly the three dimensional surface that supports the perspective view accentuates the depth of the image and accelerates the shifting perspective far more than the brain normally allows.

“This provides a powerful and often disorienting impression of depth and movement. The illusion is made possible by painting the view in reverse to the relief of the surface, that is, the bits that stick farthest out from the painting are painted with the most distant part of the scene.”

See Termespheres.

| Art

“The Anatomy of Humor”

“What is funny?” you ask, my child,
Crinkling your bright-blue eye.
“Ah, that is a curious question indeed,”
Musing, I make reply.

“Contusions are funny, not open wounds,
And automobiles that go
Crash into trees by the highwayside;
Industrial incidents, no.

“The habit of drink is a hundred per cent,
But drug addiction is nil.
A nervous breakdown will get no laughs;
Insanity surely will.

“Humor, aloof from the cigarette,
Inhabits the droll cigar;
The middle-aged are not very funny;
The young and the old, they are.

“So the funniest thing in the world should be
A grandsire, drunk, insane,
Maimed in a motor accident,
And enduring moderate pain.

“But why do you scream and yell, my child?
Here comes your mother, my honey,
To comfort you and to lecture me
For trying, she’ll say, to be funny.”

— Morris Bishop

| Poems

Well Bounded

http://commons.wikimedia.org/wiki/File:Dahala_Khagrabari.png
Image: Wikimedia Commons

In the Indian state of West Bengal lies a district known as Cooch Behar which is curiously merged with its neighbor, Bangladesh. The Indian land contains 92 Bangladeshi enclaves, and the Bangladeshi land contains 106 Indian enclaves.

The largest Indian enclave itself contains a Bangladeshi enclave, and that Bangladeshi enclave contains a bare hectare of Indian farmland known as Dahala Khagrabari. That makes Dahala Khagrabari the world’s only instance of an enclave in an enclave in an enclave.

See Concentric Landmarks.

01/23/2016 UPDATE: The two countries resolved the confusion in July 2015 by swapping enclaves. The Belgian town of Baarle-Hertog is still entertainingly confusing, though. (Thanks, Dan.)

| Oddities