Okay, that’s enough of that.
Geomagic
Hiatus
After 17 years, I think I’m going to take a bit of a break for a little while. I may post irregularly while I decide whether to continue.
In the meantime the blog archive and the podcast are still available. Thanks, as always, for reading!
Greg
P.S. Wow, thanks for all your kind messages! There are too many to respond to, but I’m reading every one. Thanks again!
Poser
A puzzle by Mel Stover:
Move the minus sign to make an expression equivalent to nine fifty.
(If you sense a trick, you’re right.)
Second Thoughts
Literary scholar Robert Hauptman calls this “marginal emendation run amok” — it’s a page from Henry James’ 1877 novel The American as James revised it anxiously for a new edition in 1907. He had decided the plot was unconvincing and asked for so many changes that two copies of the book had to be inlaid page by page on larger sheets to give him room to mark all the revisions.
On the last page, above, “James has partially or fully crossed out 16 of the 19 lines and rewritten the text for the definitive New York edition in the margins and at the foot of the page,” notes Hauptman. “His scrawling alterations cover virtually all of the generous white space and must be inserted in at least three different locations in the original text. Words are blotted out or struck in the new version, and as he approaches the bottom of the page, the lettering diminishes in size, because he realizes that he will run out of room.”
“The work on the earlier novels has involved much labour — to the best effect for the vile things, I’m convinced,” James had written to Grace Norton that March. Modern critics generally disagree — most editions today use the original version.
(From Robert Hauptman, Documentation, 2008, and Harvard’s Marks in Books, 1985.)
Black and White
By Éric Angelini. A regular chess game reached this position after Black’s fifth move. Four pieces have moved. Which ones?
The Chain Test
This is interesting — in order for a simple arch to stand, its shape when inverted must fit into the limits described by a hanging chain (a catenary).
Spanish Catalan architect Antoni Gaudí followed this principle in designing some of his buildings — he created inverted models and let the shapes of hanging chains or weighted strings determine the shapes of the arches.
The Feynman Sprinkler
In the early 1940s a curious question began to circulate among the members of the Princeton physics department. An ordinary lawn sprinkler like the one shown here would turn clockwise (in the direction of the long arrow) as its jets ejected water (short arrows). If you reversed this — that is, if you submerged the sprinkler in a tank of water and induced the jets to suck in the fluid — would the sprinkler turn in the opposite direction?
The problem is associated with Richard Feynman, who was a grad student at the time (and who destroyed a glass container in the university’s cyclotron laboratory trying to find the answer).
In fact Ernst Mach had first asked the question in an 1883 textbook. The answer, briefly, is no: The submerged sprinkler doesn’t turn counterclockwise because counterbalancing forces at the back of the nozzle result in no net torque. Experiments tend to bear this out, although in some cases the sprinkler turns slightly counterclockwise, perhaps due to the formation of a vortex within the sprinkler body.
Unanswered
During a visit to a club in 1775, Samuel Johnson was observed to put several Seville oranges into his pocket after squeezing their juice into a drink he’d made for himself. The friends who saw this “seemed to think that he had a strange unwillingness to be discovered.” Visiting Johnson the next morning and seeing the orange peels scraped and cut into pieces on a table, James Boswell asked about them:
JOHNSON. ‘I have a great love for them.’
BOSWELL. ‘And pray, Sir, what do you do with them? You scrape them it seems, very neatly, and what next?’
JOHNSON. ‘Let them dry, Sir.’
BOSWELL. ‘And what next?’
JOHNSON. ‘Nay, Sir, you shall know their fate no further.’
BOSWELL. ‘Then the world must be left in the dark. It must be said (assuming a mock solemnity) he scraped them, and let them dry, but what he did with them next he never could be prevailed upon to tell.’
JOHNSON. ‘Nay, Sir, you should say it more emphatically:–he could not be prevailed upon, even by his dearest friends, to tell.’
I don’t think this has ever been fully explained, but Boswell notes that, in a letter to Mrs. Piozzi, Johnson had once recommended “‘dried orange-peel, finely powdered,’ as a medicine.”
“The Connection”
A thought-provoking piece of nonsense by Russian absurdist poet Daniil Kharms:
Philosopher!
- I am writing to you in answer to your letter which you are about to write to me in answer to my letter which I wrote to you.
- A violinist bought a magnet and was carrying it home. Along the way, hoods jumped him and knocked his cap off his head. The wind picked up the cap and carried it down the street.
- The violinist put the magnet down and ran after the cap. The cap fell into a puddle of nitric acid and dissolved.
- In the meantime, the hoods picked up the magnet and hid.
- The violinist returned home without a coat and without a cap, because the cap had dissolved in the nitric acid, and the violinist, upset by losing his cap, had left his coat in the streetcar.
- The conductor of the streetcar took the coat to a secondhand shop and exchanged it there for sour cream, groats, and tomatoes.
- The conductor’s father-in-law ate too many tomatoes, became sick, and died. The corpse of the conductor’s father-in-law was put in the morgue, but it got mixed up, and in place of the conductor’s father-in-law, they buried some old woman.
- On the grave of the old woman, they put a white post with the inscription “Anton Sergeevich Kondratev.”
- Eleven years later, the worms had eaten through the post, and it fell down. The cemetery watchman sawed the post into four pieces and burned it in his stove. The wife of the cemetery watchman cooked cauliflower soup over that fire.
- But when the soup was ready, a fly fell from the wall, directly into the pot with this soup. They gave the soup to the beggar Timofey.
- The beggar Timofey ate the soup and told the beggar Nikolay that the cemetery watchman was a good-natured man.
- The next day the beggar Nikolay went to the cemetery watchman and asked for money. But the cemetery watchman gave nothing to the beggar Nikolay and chased him away.
- The beggar Nikolay became very angry and set fire to the cemetery watchman’s house.
- The fire spread from the house to the church, and the church burned down.
- A long investigation was carried on but did not succeed in determining the cause of the fire.
- In the place where the church had stood a club was built, and on the day the club opened a concert was organized, at which the violinist who fourteen years earlier had lost his coat performed.
- In the audience sat the son of one of those hoods who fourteen years before had knocked the cap off that violinist.
- After the concert was over, they rode home in the same streetcar. In the streetcar behind theirs, the driver was the same conductor who once upon a time had sold the violinist’s coat in a secondhand shop.
- And so here they are, riding late at night through the city: in front, the violinist and the hood’s son; and in back, the driver, the former conductor.
- They ride along and don’t know what connection there is between them, and they won’t know till the day they die.