This month I learned...

The past three or four weeks are a bit of a blur, but:

• Just before he died, Beethoven claimed to be working on a Tenth Symphony. Fragments of this were discovered among Beethoven's sketchbooks in the 1980s (!), and musicologist/composer Barry Cooper stitched together a highly speculative, but performable, first movement.

• I knew that John Harrison invented the first clock that could keep time on a ship and that such clocks cracked the longstanding problem of determining longitude at sea, leading to the first accurate maps. (H1 was his first attempt; his masterpiece, H4, was a 5-inch watch with a diamond-studded movement.) I didn't know that Harrison faced competition from an astronomical method relying on careful on-ship measurements of lunar occlusions of certain stars, huge tables of laboriously pre-calculated data, and maybe four hours of additional calculations to be done on the ship. It was a usability disaster, as one might expect. But at the time, the idea of making a clock run reliably on a pitching, rolling ship apparently seemed even crazier.

• Bill McCloskey's memoize is a replacement for make in a few lines of Python. The complete source code fits on my screen. This is the coolest hack I've seen all year.

• The word goodbye comes from the saying “God be with you”. According to the American Heritage dictionary's etymology note, “A letter of 1573 written by Gabriel Harvey contains the first recorded use of goodbye: ‘To requite your gallonde [gallon] of godbwyes, I regive you a pottle of howdyes,’ recalling another contraction that is still used.”

• According to Wikipedia, the lungfish has the largest genome of any vertebrate. But as of today, Wikipedia does not say anything about the lungfish's lungs! (I usually try to contribute in cases like this, but here I haven't a clue.)

• On the Mac, if ls -l output has an @ symbol here:

  -rw-r--r--@   1 jason  jason     54838 Sep 27  2007 #tamarin 9-25-07.colloquyTranscript

  then the file has extended attributes. These are used, for example, to mark files as “saved from the web”, triggering a warning if a user tries to open the file.