Differences (Tidal). Amounts that heights or times of high and low water at a given place differ from the corresponding heights and times at a port of reference.
Differential Block. Wheel with two sets of sprockets around its circumference, one set being on a smaller diameter than the other, and so having less sprockets. Endless chain is laid in each wheel, each having hanging bight. Weight is lifted in bight of larger wheel, power is applied to bight of lower. Difference in number of sprockets is measure of lift.
Dikrotos.* Ancient Greek vessel similar to bireme.
Dingbat. Slang term for a small swab made of rope and used for drying decks.
Dinghy. Small boat, about 10-14 ft. long, pulling two oars and fitted with mast and one or two sails.
Dioptric. Applied to lenses and lights when concentration of light rays is obtained by refraction.
Dip. Angular amount that visible horizon is below horizontal plane due to height of observer's eye. 2. Angle that a freely-suspended magnet makes with horizontal plane when aligned with lines of magnetic force. 3. To lower a flag a small distance, either as salute or signal. 4. To commence to descend in altitude. 5. To pass a rope, end of spar or other article down and under an obstruction. 6. Amount of submergence of a paddle wheel.
Diphda 114 Discipline
Diphda. Star Ceti. S.H.A. 350°; Dec. S18°; Mag. 2-2.
Dipper. Ladle used for baling a boat. 2. Name is common in U.S.A., and in Britain, for constellation Ursa Major.