Dial Wheels—The wheels constituting the motion work of a watch.
Diurnal—In an astronomical sense, pertaining to a period covering a mean solar day. See: [Solar Time].
Dog Screw—A screw with an eccentric head used to attach a watch movement to a dome case.
Dog-Watch—A nautical term for two daily two-hour periods of watching aboard ship. The first begins at 4 P. M., the other at 6 P. M.
Dolmen—A sacred instrument used for astronomical purposes at certain critical periods of the year; formed of four stones at the cardinal points and a leaning stone crossing diagonally and forming with the east stone a sacred "creep-way." The solar hours were indicated by the shadow of the leaning stone touching various prominent points or edges. One at Camp, England, is prehistoric.
Dome—The inner case of a watch which snaps on the band of a case.
Dome-Case—A case in which the inner case or dome snaps to the band of the case.
Dondi, Giacomo—Born at Padua, Italy, in 1298. In 1344 he set up at Padua a famous clock which became a model for later clocks and which earned for him the surname, "Orologio."
Double Bottom Case—A watch case in which the inner cover or bottom is made solid with the middle. The vogue in English cases for a long time; now almost obsolete.
Double-Sunk Dial—A dial in which there are two sinks; one for the hour hand, and a deeper one for the seconds hand.