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Aphelion. The point in a planet's orbit which distinguish the phenomenal diurnal motion of

is at the greatest distance from the sun. Aphellan. Castor. a Geminorum.

Aphracti. Ancient vessels with open waists. Aplanatic. Having two or more lenses of different curvatures so combined that their respective aberrations neutralize each other, and the resulting compound lens is free from spherical aberration.

Aplets. Nets for the herring fishery. Aplustre. An old word for the ornament at the bow and for the ensign at the stern.

Aplysia. A sea-hare of the genus of mollusks of the order Tectibranchiata. Some of the species have the power of throwing out a deep purple liquor, which colors the water for a con

siderable distance and serves to conceal the animal.

Apobathræ. Ancient gang-boards from the ship to the wharf.

Apogee. That point of the moon's orbit which is at the greatest distance from the earth. Formerly, on the supposition that the earth was the centre of the system, this name was given to the point in the orbit of the sun, or of a planet, which was at the greatest distance from the earth. A-poise. Balanced; properly trimmed.

Apostle. A knight-head or bollard timber. A paper sent up on appeals in the admiralty

courts.

Apothecary. The chief assistant of the medical officer. He is appointed by the surgeon for the cruise. Familiarly known as "Pills."

Appalachicola. A port of entry of Florida, on the Gulf of Mexico, at the mouth of the Appalachicola River. Pop. 1200.

Apparatus. Ammunition and equipage for

war.

Apparel. In marine insurance, the furniture of a ship; as, masts, sails, ground-tackle, guns, etc. It is a more comprehensive term than ap

paratus. Appare Appareled. Fully equipped. Apparent. (Lat. apparere, to appear.) An adjective indicating that which appears to the senses-phenomenal.

"Apparent" is sometimes equivalent to true or real, when contrasted with fictitious or imaginary. Thus the "apparent sun" is the true sun we see, as opposed to the imaginary "mean sun"; "apparent time" is reckoned by the hour-angles of the same sensible body opposed to "mean time," which is defined by the movement of the fictitious mean sun; "apparent noon" is when the true sun is on the meridian, and is distinguished from the "mean noon," which is marked by the transit of the mean sun.

"Apparent" is sometimes used as a qualification, distinguishing on the one hand from observed, and on the other from true. It is in this sense applied to elements corrected for instrumental and circumstantial sources of error, but not yet reduced to the common standard for comparison and computation. We thus have the apparent altitude" of a heavenly body, and the apparent distance" of two heavenly bodies, distinguished on the one hand from the "observed," and on the other from the "true" altitude and distance. So also there is the "apparent place" of a heavenly body in the celestial concave, and the "true place."

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"Apparent" is sometimes opposed to proper, to

the heavenly bodies resulting from the earth's rotation on her axis, from that which is due to the annual revolution of the earth in her orbit, and to the motion of each body in its orbit. Apparition. The first appearance of a star after occultation.

CIRCLE OF PERPETUAL APPARITION. A circle whose distance from the elevated pole is equal to the latitude of the place of observation. Within this circle the stars never set.

Appearance. The first making of a land-fall; formerly astronomically used for phenomenon and phase.

Appendages. The valves, gauges, etc., of a boiler. The co comparatively small portions outside the main body of the ship; as the keel, Thody Their volume is computed separudder, etc. rately and added to the main calculation to determine the displacement of a ship.

Apple-pie-order. In excellent condition; neat and trim.

Appoint. To assign or designate by authority. APPOINTED OFFICERS are petty officers shipped for the cruise for special service, and not entitled to continuous-service certificates; as, master-atarms, yeomen, etc.

An acting appointment may be issued by the commander-in-chief when a permanent vacancy occurs which cannot be filled from the supernumerary officers of other ships. This appointment must be in writing, and subject to revocation by himself, his successor, and the Secretary of the Navy. An officer holding an acting appointment wears the uniform of the grade to which he is appointed, and annexes his acting rank to his official signature.

Appointments. The various details constituting the equipment of a vessel, or the accoutrements of an officer or enlisted man.

Apportionment. The act of apportioning; a dividing into just proportions or shares; as, in the distribution of prize-money.

Appraisement. A valuation. A law instrument taken out by the captors of a vessel. Apprehend. To seize a person with a view to punishment.

Apprentice. See NAVAL APPRENTICE. Appropriation. A sum of money set apart by Congress for a particular purpose. Approve. To sanction officially.

Appulse. The near approach of one heavenly body to another, so as to form an apparent contact.

Apron. A timber conforming to the shape of the stem, and fixed in the concave part of it, extending from the head to some distance below the scarf, joining the upper and lower stempieces.

APRON OF A Dock. the sill is fastened down. APRON OF A GUN.

lock and vent.

aphelion

The platform on which

The metal cover for the

Apsides, Line of. The right line joining the phelion and perihelion points of the orbit of a planet. The term is also ap applied to the line joining the perigee and apogee of the moon. Apsis. Each extremity of the line of apsides. Apus. A constellation known as the Bird of Paradise.

Aquarius. The Water-carrier, the eleventh sign in the zodiac, which the sun enters about

the 21st of January; so called from the rains which prevail at that season in Italy and the East.

Aquatic. Inhabiting or relating to the water. Aquatites. The law-term for everything living in the water.

Aque. Wall-sided, flat-floored boats, which navigate the Rhine.

Aqueduct. A conduit or canal built for the convevance of water.

Aquila. The Eagle; a constellation in which is a very bright star (Altair) much used by navigators in taking observations.

Aquilon. The northeast wind.

Ara. The Altar; a southern constellation, containing nine stars.

Aramech. The Arabic name for the star Arcturus.

Arbalist. An engine to throw stones, or the cross-bow used for darts and arrows. Formerly arbalisters formed part of the naval force.

Arbiter. The judge to whom a matter is referred for adjustment.

Arbitrage. The referring of commercial disputes to two or more disinterested persons.

Arbitration. The settlement of disputes out of court.

Arbor. A spindle or axis.
Arby. The thrift, or sea-lavender.

Arc. A part of a circle.

DIURNAL ARC. That part of a circle, parallel to the equator, which a heavenly body describes from its rising to its setting. The nocturnal are is the arc described by the body from its setting to its rising.

THE ARC OF DIRECTION OR PROGRESSION is the are which a planet appears to describe when its motion is direct in the order of the signs.

ARC OF VISION. The sun's depth below the horizon when the stars begin to appear.

Archangel. A town of Russia, on the Dwina, 20 miles from its embouchure in the Bay of Archangel. Lat. 64° 32′ N.; lon. 40° 33′ E. This is one of the oldest ports in Russia, having been founded in 1584, and was long the only one. Pop. 20,000.

Arch-board. The part of the stern over the counter, immediately under the knuckle of the stern-timbers.

Arched Squall. See SQUALL.

Archel, Archil, or Orchil. A lichen found on the rocks of the Canary and Cape de Verde Islands. Litmus is obtained from it.

Arches. A term among seamen for the Archipelago. See GALLEY-ARCHES.

Archi

Archi-gubernus. The commander of the im

perial ship in olden times.

Archimedes' Screw. An ingenious spiral pump invented by Archimedes B.C. 260. It is also used for removing grain from a lower to a higher level. The name is applied also to the screw-propeller.

Arching. The drooping of the extremities of a vessel. See HOGGING.

Archipelago. Originally the Ægean Sea. A body of water interspersed with many islands. Architecture. See NAVAL ARCHITECTURE. Archives. Public records and papers, which are preserved as evidence of facts.

Arch of the Cove. An elliptical moulding sprung over the cove of the ship, at the lower part of the taffrail.

Arctic. Northern, or lying under Arktos, the Bear.

ARCTIC POLE. The north pole of the globe. ARCTIC OCEAN. The expanse of water within the Arctic Circle.

ARCTIC CIRCLE. A parallel distant 23°28′ from the north pole. It divides the north frigid from the north temperate zone.

Arcturus. A star of the first magnitude close to the knee of Boötes. a Boōtis.

Ardent. Said of a ship when she has a tendency to come to the wind, and keeps a strain on the weather tiller-rope.

Ardent Spirits. Distilled liquors. They are not permitted to be on board a man-of-war except as medicinal stores.

Arenaceous. Brittle; sandy; partaking of the qualities of sand.

Arenal. In meteorology, applied to a cloud of dust so thick as to prevent seeing a stone'sthrow off, common in South America, being raised by the wind from adjoining shores.

Arenation. The burying of scorbutic patients up to their neck in sand; spreading hot sand over a diseased person.

Arendal. A seaport town of Norway, 36 miles N.E. of Christiansand, on the Skager-Rack, at the mouth of the Nid-Elv. It has a customhouse and yards for ship-building. Pop. 5800. Areometer. An instrument for measuring the specific gravity of fluids; a hydrometer. dromete Argin. An old word for embankment.

Argo. The name of the ship which carried Jason and his companions on their romantic expedition to Colchis in quest of the golden fleece. Argol. The lees of wine adhering to the cask; supertartrate of potassa.

Argonauta. The paper-nautilus. The sail which it spreads is a modified arm, which invests the outer surface of the shell.

Argonauts. The company that sailed in the "Argo." A geographical society instituted at Venice, to which we are indebted for the charts and maps of Coronelli. In the United States, the men who first emigrated to California on the discovery of gold in 1849 are sometimes styled Argonauts.

Argo Navis. The constellation of the Ship, containing 9 clusters, 3 nebulæ, 540 single and 13 double stars, of which 64 are visible.

Argosy. A ship of great burden, particularly of the Levant.

Argozin, or Argnesys. The person who attended to the shackles of the galley-slaves. Argument. (Lat. argumentum, a reason.) In astronomical tables the argument is that quantity upon which the tabulated one depends, and with which, therefore, the table is "entered." Thus, in a table of correction for refraction, the altitude is the argument. When the element tabulated depends upon two given ones, then there are two arguments with which to enter the table, -one at the side, the other at the top. Thus, for the correction for the moon's altitude, the arguments of the principal table are the apparent altitude and the minutes of the moon's horizontal parallax.

Argus-shell. A species of shell beautifully variegated with spots, resembling in some measure those in a peacock's tail.

Aries, the Constellation of. (Lat. Aries, Arietis, "The Ram.") The first constellation of the

ancient zodiac, marking the period for the commemoration of the mythical golden fleece. The only two stars in it of any note are a and near together in the horns, a being the more north-wards of 5000 men were drowned, killed, or taken On the closing of the Millwall works, Mr. Hughes undertook the establishment of large iron-works in Russia, under the patronage of the government, and his hollow stringers were adopted by that government and were applied In comparing Figs. 2 and 3, it will be seen to the turreted vessel called the "Hercules" that the object of the horizontal plate of the ❘ that was building in St. Petersburg in 1871.

erly.

ARIES, THE SIGN OF. The division of the ecliptic, including the first 30° of longitude, reckoning from the first point of Aries. This origin, owing to the precession of the equinoxes, is at present in the constellation Pisces. Symbol y.

ARIES, FIRST POINT OF. The "Vernal Equinoctial Point," one of the points where the ecliptic crosses the equinoctial, so called as being the commencement of the sign Aries. See EQUINOCTIAL POINTS.

Aries. A battering-ram. (Roman Antiq.)

Aris. Sharp corners of stones in piers and docks.

Aris-pieces. Those parts of a made mast which are under the hoops.

Ark. Noah's vessel. It was 300 cubits in length, 50 in breadth, and 30 in height, and it was payed over with bitumen. A comparison of its proportions with those of the "Great Eastern" shows a considerable similarity. Reckoning the cubit at 21 inches, the length of the ark would be 525 feet, breadth 87 feet 6 inches, height 52 feet 6 inches, the "Great Eastern" being in length 680 feet, breadth 83, depth 58. It is mentioned by German commentators that Peter Jansen, in 1609, built a vessel of the same proportions as the ark, though smaller, viz.: length 120, width 20, depth 12 feet. It was found most convenient for stowage, containing one-third freight than ordinary vessels of the same tonnage, though it was unsuited for making way quickly through the water.

ARK. A mare's-tail cloud. A flat-boat.

more

Arm. A weapon. An inlet of the sea. The end of a yard, beam, bracket, or axle. A branch of the military service. One of the wings of angle-iron. The part of an anchor to which the flukes are attached. An index-hand or pointer.

TO ARMS! A summons to war or battle. UNDER ARMS. Armed and ready for fighting. TO BE IN ARMS. To be in a state of hostility. STAND OF ARMS. A complete set for one soldier, with equipments; frequently the rifle and bayonet alone.

Arm. To fit, furnish, and provide for war. To wind rope-yarns around about a cross-bar shot to facilitate ramming it home. To put tallow in the cavity at the bottom of a lead to bring up specimens of the bottom.

ARM AND AWAY! The order for armed boats to prepare for service.

Armada, The Invincible. The famous Spanish armament so called consisted of 150 ships, 2650 great guns, 20,000 soldiers, 8000 sailors, and 2000 volunteers, under the Duke of Medina Sidonia. It arrived in the Channel, July 19, 1588, and was defeated the next day by Drake and Howard. Ten fire-ships having been sent into the enemy's fleet, they cut their cables, put to sea, and endeavored to return to their rendezvous between Calais and Gravelines; the English fell upon them, took many ships, and Admiral Howard maintained a running fight from the 21st of July to the 27th, obliging the shattered fleet to Lear away for Scotland and Ireland, where a storm dispersed them, and the remainder of the primament returned by the North Sea to Spain.

The Spaniards lost fifteen capital ships in the engagement, and 5000 men; seventeen ships were lost or taken on the coast of Ireland, and upprisoners. The English lost but one ship.

Armadilla. A squadron of guarda-costas which formerly cruised on the coast of South America to prevent smuggling. Armador. A Spani

Spanish privateer.

Armament. A term expressing collectively all the great guns and small-arms, with their equipments, but generally applied to the great guns only.

Armamenta. The rigging, tackling, and all necessary furniture of an ancient ship.

Armatæ. Ancient ships fitted with sails and oars, but which fought under oars only.

Armature. A piece of soft metal connecting the poles of a magnet. It serves to prevent the dissipation of the magnetic force.

Arm-chest. A portable locker to afford a ready supply of arms and accoutrements. Armed. Supplied with weapons; fitted and furnished for war.

Armed-in-flute. Partially armed, a part of the battery having been removed and the effective armament thus reduced below that which the vessel rates.

Armed-mast. A mast made of more than one tree.

armor.

Armed Neutrality. See NEUTRALITY. Armed-ship. A vessel fitted out by private parties to cruise against an enemy's commerce. She is furnished with a letter-of-marque. Armed-stem. A prow strengthened by w strengthened by Arming. The tallow used to arm the lead. Armings. Red dress cloths, formerly hung outside the upper-works on holidays. A kind of boarding-netting.

Armipotent. Powerful in war.

Armistice. A cessation of arms for a short time by convention; a truce.

Armlet. A small arm of the sea.

Armogan. An old term for good season or opportunity for navigation, which if neglected rendered valid a claim for demurrage. A Mediterranean term for fine weather.

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Armor. The term, as now generally accepted, refers to metallic protection against the fire of artillery, whether applied to ships or forts. The metal of which armor has been heretofore composed was iron; but the development in the power of artillery has rendered it necessary to seek other metals which would be able to offer a more effective resistance to the impact of heavy shot with high velocities. Steel has been much experimented with, and has been partially adopted, and later experiments lead to the su supposition that combination of iron and steel, called "compound armor," will ultimately be in general use. A description of this combination of metals will be found under its proper heading. The thickness of armor must of course depend upon the service on which a ship is to be employed and upon her floating capacity; and, in case of forts, upon the depth of water in the approaching channels, which will determine the character of vessel that is likely to be able to approach within range; but interesting questions have arisen as to the manner in which armor should be applied, whether it should be left altogether unsupported, or whether partially supported, or whether assisted by direct support from the structure to which it is attached, or whether elastic or solid backing is the most advantageous. We will review some of these cases which have constituted the points of discussion

on armor.

Fig. 1 represents the armor-plate as applied to the "Warrior," the first regular ironclad vessel of modern times. In this case the armor is 41 inches thick, with a wood backing of 18 inches and a skin-plating of inch. The object of the iron plate is to offer a strong obstacle to the blow of the projectile, expending, unaided, its whole power of resistance in the effort. So much of the energy of the projectile as can be absorbed by the strength of the plate neutralizes that amount of the damage that might have been done to the vessel, and if the plate is destroyed it has done its duty in affording this much protection.

FIG. 1.

The wood backing acts as a cushion to save the

hull of the vessel from receiving any damage from the shock of the impact. ct. This

most simple means of applying armor. It is, in the words of an eminent constructor, "a good thickness of wood with a patch of iron on the outside," which he declared to be "the best armor in the world for ships."

An improvement on this plan of applying armor was suggested by Mr. Chalmers, of England, who, observing the easy manner in which the wood backing yielded to the force of impact, conceived the idea of reinforcing it so as to prevent it from being so readily deranged. His idea was that, as the force of impact was confined to one point, and as the wood backing naturally yielded in all directions to the pressure applied, an increased element of support could be supplied to the wood backing if this tendency could be controlled. Accordingly, he proposed that thin plates of iron should be sandwiched in, horizontally, between the layers of wood backing, so as to control in a measure the yielding of the wood in a vertical direction. These plates of iron were loosely disposed between the layers of wood, being attached neither to the skinplating nor to the armor. On this principle there was constructed in England a Chalmers target, which was fired at with very good results favoring the idea, but it was never officially adopted by the English government. Fig. 2 represents the "Warrior" armor with the Chalmers plates, as proposed by the inventor.

About the time of the experiments with the Chalmers target, the chief constructor of the English admiralty introduced into the construction of vessels, intended for ironclads, a horizontal iron girder on the outside of the hulls, which was riveted to the side by angle-irons, and which gave much additional rigidity to the hull. Fig. 3 represents the armor of the "Bellerophon," in which the horizontal

FIG. 2.

ence.

Chalmers target is achieved in the backing of the armor of the "Bellerophon," but with a differIn both instances the horizontal disposition of the iron plate between the layers of the wood backing satisfies the demand made by Mr. Chalmers for the support of the wood backing, but the proposition of Mr. Chalmers went no farther than this. His idea was simply to reinforce the backing so as to enable it to afford a more decided support to the armor; the object was to prevent the derangement of the wood backing, consequent upon impact at one point, by obstructing the vertical yielding of the wood away from the point of pressure. This effort was confined solely to the backing. But, in the "Bellerophon" armor, it will be seen that the horizontal girder, which does the work of the Chalmers plate between the layers of the wood backing, is connected with the hull of the vessel, and forms a part of the structure. This involves another and a very important consideration, for the shock of impact is thus carried to the hull of the vessel, and the consideration of the subject presents a very different aspect. A "thickness of wood with a patch patch of iron on the outside," bolted to a ship's side, is simply an independent attachment, and if the armor is shattered by the projectile, and the backing is pierced, all the independent work that can be done by this covering has been performed; but if the inner face of the armor rests against the edge of a horizontal iron plate or girder which is connected to the hull, this plate acts as a strut behind a target, and in supporting the armor it receives the force of the blow, which it communicates to the hull. A point made in defense of the use of the girder as a support to the armor is, that the force of the shock is not communicated to one point alone of the frame of the hull, but is disseminated along an extensive portion of the vessel on each side of the point of impact.

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FIG. 3.

Mr. John Hughes, of the late Millwall IronWorks, on the Thames, England, developed the idea of support to the armor-plate by the introduction of a hollow stringer, which bears his name, which was most successfully applied in the celebrated Millwall shield, a target which was fired at at Shoeburyness in 1868. The Millwall shield exhibited very superior power of resistance to all other targets that were experimented on at that time. The experiments of that year were made particularly interesting from the fact that a Rodman 15-inch gun was one of those that were used in the firing, and the inferiority of the gun in capacity to penetrate armor was made clearly perceptible. Fig. 4 represents the Hughes hollow girder or stringer, which is placed horizontally and riveted to the side of the vessel.

The hollow portion of the stringer is filled in with oak.

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girder was introduced.

The name of this vessel was afterwards changed to "Peter the Great." The hollow stringers, as applied to this vessel, were estimated to be equal to two inches of iron in increasing her defensive capacity. An objection has been made to the use of the Hughes hollow stringer on the ground that it gave too much solidity to the backing, thereby neutralizing the advantage that was supposed to rest in the elasticity afforded by the wood cushion; but the Russian authorities assert that, under the violence of the impact of a heavy projectile, there is a de

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cided amount of elasticity developed in the stringor itself, which is quite sufficient to refute the charge that the whole structure is rendered rigid by the use of this device. In the case of the Poter the Great," the Hughes stringers wore not placed in positive contact with the armor plate, but were provided with a cushion of lignum vite, about two inches thick, which Intervened between the outer face of the stringer and the inner side of the plate; this was considBrod ne a rollinement in the details of applying the stringer, which answered all objections to

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King a rapiseisinta a method of reinforcing the king for which adopted for the and hor class of monitors for the United States HAVY, but the idea has not pro4 lbyond He conception,

At De probat ims the Chalmers horizontal plats, we applied by the English admiralty, conby an angle tron to the hull and encirDeus visal, may be considered as the most addod plan of reinforcing the armor

bu maana hate, the general plan is to plate with iron the stone-works already constructed, and, at Spithead, for example, the sams plan is carried out with now fortifications; but a notalde exception is made to Mods fule by the Russians in the now works which they java satablished for the desnes of St. Petersburg at Crestadt. A description of the different systems of In this donese will be the best citaatos coche ed much plans for defense thod worthy of being adopted. the head her channel the defenses Curly d lucrate, constructed on the dedallion as wond in the English Lids totdelde plating of these Sale Hack, and the hollow backing.

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the to the of the channel there are ranted butterine, the armor of

1. in Jon le cu that of all the others.

FIG. 6.

ported by horizontal girders of iron, 12 inches wide, riveted to an inner 1-inch skin, all of which is backed by struts, which serve to divide the interior space in the battery allotted to the service of each.

Fig. 7 represents the armor of the second battery, which is constructed on the same plan as that of the first battery, with the exception of the girders and the inner skin, the 1-inch plate behind the wood backing forming the inner skin. In this plan the wood backing is increased to 18 inches thickness.

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FIG. 7.

Fig. 8 represents the armor of the third battery, which is calle called the Lancaster armor. The edges of the plates are tongued and grooved, and are built up one upon the other. A part of each plate has a thickness of 14 inches, while the rest of the same plate is 8 inches thick. The inner side of this armor presents a surface of horizontal ribs, the exterior surface is smooth, the inequality of the thickness of each plate being confined to the inner side. The armor is supported behind by iron uprights, having on one surface projecting squares, which enter into the recesses between the ribs of the plates. These uprights are separated by intervals of 2 or 3 feet. The whole is backed by struts.

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Fig. 9 represents the fourth battery with its armor. This battery is built of granite blocks of Finland stone, 10 feet thick. This is covered by 2 inches of teak, on which is placed the armor, consisting of plates 9 inches in thickness. This construction not requiring the support of struts, the battery is quite open from one end to the other, which gives the beautiful stone an opportunity of showing to advantage.

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Fig. 10 represents the fifth battery, which has 9 inches of armor on the exterior. Behind this there are placed uprights of iron 6 inches square

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