This 732K QuickTime movie reproduces a very, very short clip from the 1951 George Pal sci-fi epic, "When Worlds Collide." I think this must be a real shot of the Bush Differential Analyzer (1940's 100%-mechanical analog computer). Anybody know any more? Could this really be what it sounded like? It sounds like relays clicking, doesn't it? Knowing Hollywood, if the director didn't think the authentic sound of the Bush Differential Analyzer was dramatically correct, they could well have substituted some other sound. Anybody know of any better movies of the Bush Differential Analyzer in action? Comments to after removing nine 9's from the address.

Boy, is this ever a lousy subject for MPEG compression! After experimenting with several settings I gave up and decided to use the most compressed. Even at a setting where the file size was 5 meg, all the little rotating frobs were still disintegrating into piles of pixel-crumbs. So since there was no way to make it good, I decided to use a setting that at least makes it small. If you want to see what the film really looks like, rent the video--my local Blockbuster has it, yours probably does, too. (There is also a similar, but even shorter shot in Destination, Moon).

Analog computers are a lost art, and mechanical analog computers are surely a lost art. But I guess they were very important during World War II, and the MIT Radiation Lab did a lot of work on computing linkages when they weren't busy with radar. I remember reading about the Bush Differential Analyzer. Very ingenious; there needed to be high-precision torque amplifiers to keep regenerating and boosting the output from the output shafts so that they would be capable of driving the next stage. I'd love to know just how problems got set up. The parameter ranges were very restricted, and it must have been quite an art spend a lot of time analyzing and transforming the equations to scale them into range... couldn't have any intermediate variables that would require a shaft to spin at 1,000,000 rpm.

I remember an old cartoon in Mad magazine that shows someone being thrown into the guts of a "Univac," depicted as full of terrifying-looking gears and cams. I suspect this must have been inspired by the Bush differential analyzer, which does look like something out of a cartoonist's nightmare (if that's what this is). From the looks of it, you wouldn't want to have the tip of your necktie land in that thing.