In 1945, Oxford University’s Museum of the History of Science realized that 14 astrolabes were missing from its collection. Curator Robert T. Gunther had arranged for storage of the museum’s objects during the war, but both he and the janitor who had helped him had died in 1940. The missing instruments, the finest of the museum’s ancient and medieval astrolabes, were irreplaceable, the only examples of their kind. Where had Gunther hidden them?

The museum consulted the Oxford city police and Scotland Yard, who searched basements and storerooms throughout the city. The Times, the Daily Mail, and the Thames Gazette publicized the story. Inquiries were extended to local taxi drivers and 108 country houses. At Folly Bridge, Gunther’s house, walls were inspected, flagstones lifted, and wainscoting prised away. A medium and a sensitive were even consulted, to no avail. Finally the detective inspector in charge of the case reviewed the evidence and composed a psychological profile of Gunther, a man he had never met:

Clever professor type, a bit irascible, who didn’t get on too well with his colleagues. Single minded. Lived for the Museum. Hobby in Who’s Who ‘… founding a Museum’. Used to gloat over the exhibits and looked upon them as his own creation. Never allowed anyone else to handle them. Reticent, even secretive. Never told anyone what he what he was going to do. Didn’t trust them, perhaps. Not even his friends the Rumens, who would have offered their car to move the things. Had original ideas though. Safe from blast below street level. Germans would never bomb Oxford. Why, its total war damage was £100 and that from one of our own shells. How right he was. He never expected to die then. Believed he’d live to 90. Hadn’t made any plans; like most of us he thought he might get bumped off when the war started. That’s what he was telling his son in those letters. There was only one conclusion with a man like that anyhow: he’d never let the things out of his reach if he could have helped it. Didn’t even take the trouble to pack his own treasures away in Folly Bridge.

In 1948 the new curator found the missing instruments — they were right “within reach” in the museum’s basement. Gunther had disguised their crate with a label reading “Eighteenth-Century Sundials,” and it had evaded detection throughout the searches.

From A.E. Gunther, Early Science in Oxford, vol. XV, 1967, 303-309.

(Thanks, Diane.)

If we stand immediately below a painting in a gallery, it appears foreshortened. But if we stand on the other side of the room, it appears small. Somewhere between these two points must be the optimum viewing position, where the painting fills the widest possible angle in our vision. How can we find it?

The German mathematician Regiomontanus posed this question in 1471. We can solve it using calculus, but it also yields to simple geometry: Draw a circle defined by the top and bottom of the painting and our eye level. That’s the point we want — any other point at eye level will define a larger circle, in which the picture makes a smaller chord and subtends a smaller angle.

(Thanks, David.)

The Pythagorean theorem works for any similar shapes, not just squares.

In the figure above, A + B = C.

If the three sides of a right triangle are made the diameters of three circles, then the combined area of the two smaller circles equals that of the largest. That’s also the area of the circumcircle, since a right triangle’s hypotenuse forms the diameter of its circumscribing circle.

In 1986 Lee Sallows invented the alphamagic square — spell out each number in this magic square and count its letters (25 -> TWENTY-FIVE -> 10), and you’ll produce another magic square:

David Brooks points out that this works also in Pig Latin.

Sallows extends the idea into geometry:

How many ideas hover dispersed in my head of which many a pair, if they should come together, could bring about the greatest of discoveries! But they lie as far apart as Goslar sulphur from East India saltpeter, and both from the dust in the charcoal piles on the Eichsfeld — which three together would make gunpowder. How long the ingredients of gunpowder existed before gunpowder did! There is no natural aqua regia. If, when thinking, we yield too freely to the natural combinations of the forms of understanding and of reason, then our concepts often stick so much to others that they can’t unite with those to which they really belong. If only there were something in that realm like a solution in chemistry, where the individual parts float about, lightly suspended, and thus can follow any current. But since this isn’t possible, we must deliberately bring things into contact with each other. We must experiment with ideas.

— G.C. Lichtenberg, Aphorisms