DITCH. In fortification the excavation in front of the parapet of any work, ranging in width from a few feet in field fortification to thirty or forty yards in permanent works, having its steep side next the rampart called the escarp: the opposite one is the counterscarp. Its principal use is to secure the escarp as long as possible. There are wet ditches and dry ones, the former being less in favour than the latter, since a dry ditch so much facilitates sorties, counter-approaches, and the like. That kind which may be made wet or dry at pleasure is most useful. DITTY-BAG. Derives its name from the _dittis_ or Manchester stuff of which it was once made. It is in use among seamen for holding their smaller necessaries. The ditty-bag of old, when a seaman prided himself on his rig, as the result of his own ability to fit himself from clue to earing, was a treasured article, probably worked in exquisite device by his lady-love. Well can we recollect the pride exhibited in its display when "on end clothes" was a joyful sound to the old pig-tailed tar. DITTY-BOX. A small caddy for holding a seaman's stock of _valuables_. DIURNAL ARC. That part of a circle, parallel to the equator, which is described by a celestial body from its rising to its setting. DIURNAL PARALLAX. _See_ PARALLAX. DIVE, TO. To descend or plunge voluntarily head-foremost under the water. To go off deck in the watch. A ship is said to be "_diving into it_" when she pitches heavily against a head-sea. DIVER. One versed in the art of descending under water to considerable depths and abiding there a competent time for several purposes, as to recover wrecks of ships, fish for pearls, sponges, corals, &c. The diver is now a rating in H.M. ships; he may be of any rank of seaman, but he receives £1, 10_s._ 5_d._ per annum additional pay--one penny a-day for risking life! Also, a common web-footed sea-bird of the genus _Colymbus_. DIVERGENT. A stream flowing laterally out of a river, contradistinguished from convergent. DIVERSION. A manœuvre to attract, wholly or partially, the enemy's attention away from some other part of the operations. DIVIE-GOO. A northern term for the _Larus marinus_ or black-backed gull. DIVINE SERVICE. Ordered by the articles of war, whenever the weather on a Sunday will allow of it. DIVING-APPARATUS. Supplied to the flag-ship, and also a man with the title of diver, to examine defects below water. DIVING-BELL. Used in under-water operations for recovering treasure, raising ships, anchors, &c. DIVING-DRESS. India-rubber habiliments, the head-piece is of light metal fitted with strong glass eyes, and an attached pliable pipe to maintain a supply of air. The shoes are weighted.