The Spool Paradox

When a thread is pulled horizontally from the underside of a wound spool, the spool rolls in the direction of the pulling force, counter to intuition. When the thread is pulled upward vertically, the spool rolls in the opposite direction.

Why the difference? The spool must rotate about its point of contact with the table, but the direction of torque, clockwise or counterclockwise, varies with the angle of the thread. Interestingly there’s a critical angle at which the spool does not roll but slides.

| Science & Math

Trompe L’Oeil

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[Parrhasius], it is recorded, entered into a competition with Zeuxis, who produced a picture of grapes so successfully represented that birds flew up to the stage-buildings; whereupon Parrhasius himself produced such a realistic picture of a curtain that Zeuxis, proud of the verdict of the birds, requested that the curtain should now be drawn and the picture displayed; and when he realized his mistake, with a modesty that did him honour he yielded up the prize, saying that whereas he had deceived birds Parrhasius had deceived him, an artist.

From Pliny the Elder, Naturalis Historia. See Demo.

| Art

The Chapel Oak

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In 1696 lightning struck an oak in Normandy, and the resulting fire hollowed out the tree. Villagers filled the space with two chapels, reached by a spiral staircase that circles the trunk. Now perhaps a thousand years old, the Chêne chapelle is still in use today.

See Al Fresco.

| Oddities

Asked and Answered

Tennyson was plagued by autograph hunters.

As a pretext, one wrote to him asking which was the better dictionary, Webster’s or Ogilvie’s.

He replied by cutting the word Ogilvie’s from the letter, pasting it to a blank sheet of paper, and mailing it back.

See Pen Fatigue.

| Literature · Society

Empty Promises

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By substituting images for claims, the pictorial commercial made emotional appeal, not tests of truth, the basis of consumer decisions. The distance between rationality and advertising is now so wide that it is difficult to remember that there once existed a connection between them. Today, on television commercials, propositions are as scarce as unattractive people. The truth or falsity of an advertiser’s claim is simply not an issue. A McDonald’s commercial, for example, is not a series of testable, logically ordered assertions. It is a drama — a mythology, if you will — of handsome people selling, buying and eating hamburgers, and being driven to near ecstasy by their good fortune. No claims are made, except those the viewer projects onto or infers from the drama. One can like or dislike a television commercial, of course. But one cannot refute it.

— Neil Postman, Amusing Ourselves to Death, 1985

| Society

Voice Flowers

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In 1885, seeking a way to depict vocal sounds visually, Welsh singer Megan Watts Hughes invented the eidophone, a chamber capped with an elastic membrane that would resonate when the singer sang into a tube. When she spread the disk with a thin layer of sand or glycerine, standing waves would register as visible patterns resembling forget-me-nots, daisies, marigolds, chrysanthemums, and sunflowers.

“Stepping out of doors,” she wrote, “[I] have seen their parallels living in the flowers, ferns, and trees around me; and … the hope has come to me that these humble experiments may afford some suggestions in regard to nature’s production of her own beautiful forms.”

The field of study she helped to pioneer is now known as cymatics — see Chladni Figures.

| Art · Science & Math

Regularity

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You know the watch argument was [William] Paley’s greatest effort. A man finds a watch and it is so wonderful that he concludes that it must have had a maker. He finds the maker and he is so much more wonderful than the watch that he says he must have had a maker. Then he finds God, the maker of the man, and he is so much more wonderful than the man that he could not have had a maker. This is what the lawyers call a departure in pleading.

— Robert G. Ingersoll, “Why I Am an Agnostic,” 1896

| Religion