DETONATING HAMMER. A modern introduction into the Royal Navy for firing the guns. With the aid of an attached laniard, it is made to descend forcibly upon the percussion arm of the tube, and fires the piece instantaneously. It is, however, already generally superseded by the use of the _friction-tube_ (which see). DEVIATION. A voluntary departure from the usual course of the voyage, without any necessary or justifiable cause: a step which discharges the insurers from further responsibility. Liberty to touch, stay, or trade in any particular place not in the usual course of the voyage must be expressly specified in the contract, and even this is subordinate to the voyage. The cases of necessity which justify deviation are--1, stress of weather; 2, urgent want of repairs; 3, to join convoy; 4, succouring ships in distress; 5, avoiding capture or detention; 6, sickness; 7, mutiny of the crew. It differs from a _change_ of voyage, which must have been resolved upon before the sailing of the ship. (_See_ CHANGE.)--_Deviation_ is also the attraction of a ship's iron on the needle. It is a term recently introduced to distinguish a sort of second variation to be allowed for in iron vessels. DEVIL. A sort of priming made by damping and bruising gunpowder. DEVIL-BOLTS. Those with false clenches, often introduced into contract-built ships. DEVIL-FISH. The _Lophius piscatorius_, a hideous creature, which has also obtained the name of fish-frog, monk-fish, bellows-fish, sea-devil, and other appellatives significant of its ugliness and bad manners. There is also a powerful _Raia_, which grows to an immense size in the tropics, known as the devil-fish, the terror of the pearl-divers. _Manta_ of Spaniards. DEVILRY. Spirited roguery; wanton mischief, short of crime. DEVIL'S CLAW. A very strong kind of split hook made to grasp a link of a chain cable, and used as a stopper. DEVIL'S SMILES. Gleams of sunshine among dark clouds, either in the heavens or captain's face! DEVIL'S TABLE-CLOTH. _See_ TABLE-CLOTH. DEVIL TO PAY AND NO PITCH HOT. The seam which margins the water-ways was called the "devil," why only caulkers can tell, who perhaps found it sometimes difficult for their tools. The phrase, however, means service expected, and no one ready to perform it. Impatience, and naught to satisfy it. DEW-POINT. A meteorological term for the degree of temperature at which the moisture of the atmosphere would begin to precipitate; it may be readily ascertained by means of the hygrometer. DHOLL. A kind of dried split pea supplied in India to the navy. DHONY, OR DHONEY. A country trading-craft of India from 50 to 150 tons; mostly flat-bottomed. (_See_ DONEY.)