JIGGER, a machine, consisting of a piece of rope about five feet long, with a block at one end and a sheave at the other; and used to hold-on the cable, when it is heaved into the ship by the revolution of the windlass. See Holding-on.
The jigger is particularly useful when the cable is either slippery with mud or ooze, or when it is stiff and unwieldy; in both of which cases it is very difficult to stretch it back from the windlass by hand, which however is done with facility and expedition, by means of the jigger, as follows: the end of the rope, to which the sheave is fastened by a knot, is passed round the cable close to the windlass, and the hind part of the rope coming over the sheave, is stretched aft by means of another rope passing through the jigger-block. As soon as the last rope is extended, the turn of the former about the cable is firmly retained in its position, by the compression of its hind part under the sheave, acting upon what may be called the neck of the jigger. But as the cable continues to be heaved into the ship, it is evident that the jigger, which is fastened on a particular part thereof, stretching it back, will be removed further aft, by every turn of the windlass, and the effort of the jigger will be lessened in proportion to its distance from the windlass: this circumstance renders it necessary to fleet it, or replace in a proper state of action, as occasion requires. The man who performs this office accordingly calls out, fleet, jigger! one of the men, at the windlass, instantly fixes his handspec between the deck and the cable, so as to jam the latter to the windlass, and prevent it from running out till the jigger is refixed.
Jigger-Tackle, a light small tackle, consisting of a double and single block, and used on sundry occasions by seamen. See Tackle.
IN, dedans, the state of any of a ship’s sails, when they are furled or stowed. It is used in this sense also in opposition to out, which implies that they are set, or extended to assist the ship’s course.
INSURANCE, assurance, a certain contract, by which an individual, or company, agrees to indemnify whatever losses or damages may happen to a ship or cargo, during a voyage, provided they are not occasioned by default of the person insured. For this agreement the latter pays a certain sum in advance, called the præmium, which accordingly falls to the insurer, in case the ship arrives in a safe harbour; but if the ship is lost, the insurer renders the stipulated sum to the merchant.
JOURNAL, in navigation, a sort of diary, or daily register of the ship’s course, winds, and weather; together with a general account of whatever is material to be remarked in the period of a sea-voyage.
In all sea-journals, the day, or what is called the 24 hours, terminates at noon, because the errors of the dead-reckoning are at that period generally corrected by a solar observation. The daily compact usually contains the state of the weather; the variation, increase, or diminution of the wind; and the suitable shifting, reducing, or enlarging the quantity of sail extended; as also the most material incidents of the voyage, and the condition of the ship and her crew; together with the discovery of other ships or fleets, land, shoals, breakers, soundings, &c.
The form of keeping journals is very different in merchant-ships; but one method appears to be invariably pursued in the navy, which nevertheless is certainly capable of improvement, because no form can be properly called perfect, that leaves as great a space for one day’s work, the matter of which may be contained in very few lines, as for another that abounds with important incidents, so as to occupy ten times the space. If therefore there be any such thing as propriety of method on this occasion, it seems to imply, that the space containing, should conform to the matter contained, which will necessarily be greater or less, according to circumstances.
IRON-WORK, ferrure, a general name for all the pieces of iron, of whatsoever figure or size, which are used in the construction of a ship: as bolts, boom-irons, nails, spikes, chains and chain-plates, block-strops, cranks, braces, pintles, and googings.
The most material of these articles are explained in their proper places; but as the article bolt, of which the figures are represented in plate [II]. was accidentally omitted in the proper place, according to the plan of this work, it may not be improperly introduced here.