The old destroyer gun turret which housed our card-gap* setup had become a bit frayed and tattered from the shrapnel it had contained. (The plating on a destroyer is usually thick enough to keep out the water and the smaller fish.) So we had installed an inner layer of armor plate, standing off about an inch and a half from the original plating. And, as the setup hadn’t been used for several months, a large colony of bats —yes, bats, little Dracula types —had moved to the gap to spend the winter And when the first shot went off, they all came boiling out with their sonar gear fouled up, shaking their heads and pounding their ears. They chose one rocket mechanic —as it happens, a remarkably goosy character anyway—and decided that it was all his fault. And if you, gentle reader, have never seen a nervous rocket mechanic, complete with monkey suit, being buzzed by nine thousand demented bats and trying to beat them off with a shovel, there is something missing from your experience.
John D. Clark
I G N I T I O N !: An Informal History of Liquid Rocket Propellants, page 171
[I love this book.—Joe]
* The card-gap test is used to determine the shock sensitivity of a potentially explosive liquid. A 50-gram block of tetryl (high explosive) is detonated beneath a 40 cc sample of the liquid in question, contained in a 3″ length of 1″ iron pipe sealed at the bottom with a thin sheet of Teflon. If the liquid detonates, it punches a hole in the target plate, of 3/8″ boiler plate, sitting on top of it. The sensitivity of the liquid is measured by the number of “cards,” discs of 0.01″ thick cellulose acetate, which must be stacked between the tetryl and the sample to keep the latter from going off. Zero cards means relatively insensitive, a hundred cards means that you’d better forget the whole business. As may be imagined, the test is somewhat noisy, and best done some distance from human habitation, or, at least, from humans who can make their complaints stick.