United States. Army. Signal Corps · Washington · leaf 107
the card is suspended on an almost frictionless point and is free to maintain its direction when the airplane is turned. The pivot itself is fixed to the center of a bowl called the “ compass bowl.” This bowl is covered by a glass plate or a hole is cut in it to which the glass plate is fixed. All… … the needle come to rest quickly, so that it very soon points to the north after a turn has been made. On the bowl of the compass will be found a mark called the “lubber’s point,” and when mounting a compass in an airplane this point should be in the fore-and-aft line of the airplane and pointing…
Aeronautics, Military
Internet Archive · Smithsonian Libraries · Public domain (published before 1931). Free to use for anything.
