DICTIONARY OF

Diacoustics 113 Dip
Diacoustics. Science of direct sound.
Diagonal. Any knee, plank, brace, etc., that is placed diagonally. 2. Line cutting a body plan
in an oblique direction.
Diagonal Built. Said of wooden boats and vessels in which side planking is made up of two
layers at an angle of 45° with keel, upper layer crossing lower layer in opposite directions.
Diamagnetic. Name given to substance whose magnetic permeability is less than unity. 2. A
substance which, when magnetised, lies across lines of magnetic force.
Diametral Plane. Great circle of a sphere.
Diamond Knot. Fancy bend in two ropes' ends made by interlacing them. Similar to
'Carrick Bend'. 2. Knot formed in a rope, somewhat similar to single 'Turk's Head'.
Diaphone. Sonic fog-signalling apparatus that gives a high note that descends to a low note
of great carrying power. Fitted in light vessels.
Diatomic Ooze. Yellowish-brown ooze containing the algae 'bacillareophyta'. Found at
depths from 600 to 2000 fathoms.
Dicrotum.* Boat propelled by two oars.
Dielectric. Insulating material that prevents conduction of electricity but allows induction.
Used in electrical condensers.
Diesel Engine. Oil engine in which ignition of fuel is caused by compression. Cycle
comprises air compression, fuel injection, ignition, and scavenging. Cycle may be completed
in two or four strokes.
Difference of Latitude. Angular value of arc of meridian intercepted between parallels of
latitude passing through two different positions.
Difference of Longitude. Angle at pole, or intercepted arc of Equator, between two
meridians.
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.