(Roughly) Daily

“‘It’s magic,’ the chief cook concluded, in awe. ‘No, not magic,’ the ship’s doctor replied. ‘It’s much more. It’s mathematics.’*…

Michael Wendl (and here) dissects some variants of the magic separation, a self-working card trick…

Martin Gardner—one of history’s most prolific maths popularisers [see here]—frequently examined the connection between mathematics and magic, commonly looking at tricks using standard playing cards. He often discussed ‘self-working’ illusions that function in a strictly mechanical way, without any reliance on sleight of hand, card counting, pre-arrangement, marking, or key-carding of the deck. One of the more interesting specimens in this genre is a matching trick called the magic separation.

This trick can be performed with 20 cards. Ten of the cards are turned face-up, with the deck then shuffled thoroughly by both the performer and, importantly, the spectator. The performer then deals 10 cards to the spectator and keeps the remainder for herself. This can be done blindfolded to preclude tracking or counting. Not knowing the distribution of cards, our performer announces she will rearrange her own cards ‘magically’ so that the number of face-ups she holds matches the number of face-ups the spectator has. When cards are displayed, the counts do indeed match. She easily repeats the feat for hecklers who claim luck…

All is revealed: “An odd card trick,” from Chalkdust (@chalkdustmag).

* David Brin, Glory Season

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As we conjure, we might spare a thought for Persian polymath Omar Khayyam; the mathematician, philosopher, astronomer, epigrammatist, and poet died on this date in 1131.  While he’s probably best known to English-speakers as a poet, via Edward FitzGerald’s famous translation of the quatrains that comprise the Rubaiyat of Omar Khayyam, Omar was one of the major mathematicians and astronomers of the medieval period.  He is the author of one of the most important works on algebra written before modern times, the Treatise on Demonstration of Problems of Algebra (which includes a geometric method for solving cubic equations by intersecting a hyperbola with a circle).  His astronomical observations contributed to the reform of the Persian calendar.  And he made important contributions to mechanics, geography, mineralogy, music, climatology, and Islamic theology.

Written by (Roughly) Daily

December 4, 2021 at 1:00 am

In memoriam…

From the sublime to the ridiculous is but a step.

Napoleon, on the invasions of Russia (10 December 1812),as recorded by Abbé du Pradt

“Napoleonland”, the brainchild of former French minister and history buff Yves Jégo, is being touted as a rival to Disneyland – assuming, that is, it can gather the £180 million needed to leave the drawing board.

The plan is to build the unlikely amusement park on the site of the brilliant but doomed French leader’s final victory against the Austrians in the Battle of Montereau in 1814 just south of Paris.

With its reenactments (including a water show re-staging of Trafalgar), a ski run through a battlefield “surrounded by the frozen bodies of soldiers and horses,” and a recreation of Louis XVI being guillotined during the revolution, “it’s going to be fun for the family,” Mr Jégo promises.

Read the whole story in The Telegraph.

As we contact our travel agents, we might compose a birthday verse in dactylic hexameter for Decimus Iunius Iuvenalis, AKA Juvenal; the author of the Satires was (at least insofar as tradition has it; the records are scant-to-the-point-of-nonexistent) born on this date in 55 CE.

quis custodiet ipsos custodes (Who will watch the watchmen?)

Satires, 6.347-48

Frontispiece of Dryden’s translation of Satires (source)

Written by (Roughly) Daily

March 2, 2012 at 1:01 am

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