Whether it’s another kind just depends on how you define the first kind, right? Each is part of the inside of a cube; slice off just a corner, or two corners. Although waves and wind make the buoys bob around, the sea is roughly flat (pun intended), so the desired reflection from/to ship radars is essentially confined to a plane. I suspect almost all of the reflection is from the vertical planes of metal, very little from the horizontal ones. Flash bulbs had not only magnesium wool, but the gas inside was (relatively) pure oxygen! If the glass happened to shatter, the plastic-like coating contained it. That coating usually blistered heavily when the bulb went off. — Mike

On Jan 2, 2020, at 5:02 PM, Bill Gosper <billgosper@gmail.com> wrote:

E.g., square? big-red-buoy-removed-from-florida-beach-after-sitting-there-for-days <https://www.foxnews.com/us/big-red-buoy-removed-from-florida-beach-after-sitting-there-for-days> (Kids, check out https://en.wikipedia.org/wiki/Corner_reflector . Three bounces and the laser beam returns to its source. But likewise, a bundle of *uncolilmated* beams!

I've always wanted to put an anemometer made of corner reflectors on my car to confuse the heck out of police radar. Radar return ordinarily drops off with the *fourth power* of distance. But only 2nd power with a corner reflector. That's huge. Stealth in reverse. Radar transmitters are loud. In the 60s, I worked at a naval air station where a visiting photographer was severely burned when all the flashbulbs <https://upload.wikimedia.org/wikipedia/commons/f/fa/Brownie_Hawkeye_with_Flash.jpg> went off in his pockets. (That sparkly stuff is "magnesium wool"!)) —rwg _______________________________________________ math-fun mailing list math-fun@mailman.xmission.com https://mailman.xmission.com/cgi-bin/mailman/listinfo/math-fun