A. Ab´a-cis′cus.

A small square stone or tessera for a tesselated pavement. Ab′a-cus.

An instrument used from time immemorial in performing the operations of addition and subtraction.

A smooth board with a marginal ledge formed the writing and calculating table of the Greek schoolboys and accountants. For writing, it was strewn with sand, upon which marks were made with a stylus; thus they learned to write, and on this they executed geometrical figures. The primary use of the board is indicated by its name, which is derived from the first three letters of the Greek alphabet, *a *b *l. It was called an abax, and retains the name, but slightly modified.

The abax strewed with sand is the pulvis eruditus, or the Mensa Pythagorca of classic authors.

For arithmetical calculation, the same board was used without the sand, to contain the counters, which were arranged thereon in parallel rows, representing respectively units, tens, hundreds, thousands, etc. Solon (about 600 B. C.) refers to the arbitrary denominations of the several lines, in a metaphor which compares the different grades of society to the different values of the counters in the several rows.

The counters were pebbles, beans, or coins, especially the former. The Greek word for the counters of the abacus was derived from a word signifying a pebble. Pythagoras, the great arithmetician, hated beans, — an antipathy he derived from the Egyptian priests, his instructors. About the same time Daniel was eating pulse in Babylon without grumbling, and Horatius was hewing down the bridge of the Janiculum.

The Roman word calculus, from which we derive our word calculate, was the diminutive of calx, a stone, and referred to the pebbles which formed the counters of the abacus.

Sometimes the counters were shifted to the right in counting, sometimes to the left. It is stated that the Greek and Roman practices differed in this respect. Several varieties of instruments are represented on the ancient monuments.

The step was easy from a flat board with shifting counters arranged in rows, to a board with grooves in which the pebbles were rolled. Afterwards we find pellets strung upon wires, and thus the Chinese have used it for ages.

The illustration shows the last-mentioned form of the device, arranged for decimal counting. The number indicated by the beads on the right hand of the frame is 198,764, and it will be seen that by transposing the beads to one side or the other, as required, either addition or subtraction may be readily performed. A person accustomed to the instrument will perform these operations with great rapidity and accuracy. The Chinese term the instrument a swan-pwan, and are very dexterous in its use.


The original of the Chinese abacus has been supposed to be the "knotted cord," used in China for keeping accounts before the invention of writing. The knots are made movable by substituting sliding beads. Hence like wise seems to have been derived the mode of keeping the Chinese Tung-tien, or perforated coins, which are strung upon a cord.

One form of the Chinese abacus has two compartments, five beads in one and two in the other; the former have the value of one each, the latter five each. The wires are nine in number, and each runs through the two compartments.

The Romans, contrary to the customs of the Phœ- nicians and Greeks, from whom they received their alphabet, expressed their numbers 1, 2, 3, not by the first letters of the alphabet, but by strokes, I II III; in this respect unconsciously copying the Chinese numerals of the same value, — — — — — — The difference in the direction of the figures gives the numerals in each the same position across the column; for the Roman writing is in horizontal column, the Chinese vertical.

The resemblance between the Chinese and Roman numerals extends much further than the above, and shows a common origin.

Perhaps it may be accounted for by the studies of Pythagoras in India, and the subsequent instruction of Numa in the school founded by the sage of Samos in Crotona, a city of Magna Græcia. (Plutarch.)
Hindoo (commonly known as "Arabic").Roman.Chinese.
The resemblance cannot be accidental. Pythagoras and Kung-fu-tze (Confucius) were contemporaries.

Another mode among the Chinese of expressing 20, 30, etc. was by placing 2, 3, etc. before the sign of ten; so that they in some degree anticipated the Hindoo, where a numeral before the zero expressed so many tens, e. g.

The great advance in the Hindoo over the other systems of notation was in giving a place value to figures. In Sanscrit, the initial letters of the Sanscrit names of the Indian numerals are employed from 1 to 9. The original zero was a dot. The Greek letter omicron (o) was afterwards substituted, and forms our naught. It is amusing to see the combination of Hindoo and Roman figures during the fourteenth and fifteenth centuries, such as
(Written.)(To be read.)
x 313
x 414
40 141, etc.
Showing that the force of the zero and the value from position were not understood at first, even when the new characters had become customary.

The decimal and duodecimal systems of arithmetic were in use in Egypt at the earliest period of its known history. For the respective systems the numbers of counters in the rows would vary, each line representing a multiple by 10 or 12 of the line below it. There is no representation of the abacus for counting on the Egyptian monuments. "The Assyrians counted by 60's as well as by 100's."—Rawlinson.

The instrument was probably invented by the Chinese, and passed thence westwardly through India and Arabia to Europe. The evidences of ancient trade on this line are found at both ends and at intermediate points. The glass bottles with Chinese inscriptions, found with the Egyptian mummies, prove the existence of trade relations between those nations before the founding of Athens, and also dissipate the myth of Pliny as to the discovery of glass by certain mariners of Phœnicia, a few centuries previous to the time at which he made his curious collection of vagabond information.

Over this famous route travelled the mariner's compass, gunpowder, the art of glazing pottery, of making paper of pulp, and much else that we value. Felting of animal fiber was also derived from Asia, but probably entered Europe by a more northern route.

The Greek and Roman numeration was decimal, but their system of notation was very unfortunate, as any one may ascertain by trying a sum in multiplication: CCXLVIII XLV ——— ?

The Oriental system of notation was introduced by the Arabs, and was credited to them, but they more properly term them Indian numerals, referring to their derivation from the Hindoos. This system of notation passed with the Saracens along the northern coast of Africa, and was carried by them into Spain. The caliphate of Cordova was established by Abderahman, A. D. 755, and the university at that place was founded A. D. 968. At this distinguished seat of learning was educated the famous Gerbert of Auvergne. This enlightened ecclesiastic was successively a schoolmaster at Rheims (where he introduced the abacus, the Arabic numerals, the clock, the organ, and the globe), archbishop of Ravenna, and, eventually, Pope Sylvester II., to which position he was elevated by the decree of the Emperor Otho III. Patron and prelate died of poison shortly after, about A. D. 1002.

Gerbert was probably the first to use in a Christian school the nine digits and a cipher, which proved, as William of Malmesbury said, "a great blessing to the sweating calculators."

A translation of Ptolemy, published in Spain in 1136, used the Hindoo notation. The Hindoo numerals were introduced into England about A. D. 1253.

The accounts of the kings of England, previous to the Norman Conquest—and the same is probably true of most contemporary European nations—were calculated by rows of coin disposed as in the abacus, that is, placed in parallel rows which represented gradually increasing denominations in the ascending series. At the Conquest an amplification of the same idea was introduced, the calculations being performed by the teller, at a large table called a sac- carium. This had a ledge around it, and was covered by a black cloth ruled with chequer lines. Hence the word Exchequer, as applied to English national finances.

In the twelfth century, this table was five by ten feet, and its cloth cover was divided by vertical and horizontal lines. The horizontal bars represented pence, shillings, pounds, tens, hundreds, thousands of pounds. Coins were used for counters; the first and lowest bar advanced, by dozens, the number of pence in the shilling; the second, by scores, the number of shillings in the pound; the higher denominations by tens. This was a true abacus, and was used down to a comparatively recent period.

The accounts of merchants were kept in Roman numerals till the close of the sixteenth century, and the use of the abacus was maintained to a much later date. Until 1600 its use was a branch of popular education.

Offices for changing money came to be indicated by a checker-board, and the sign was afterwards appropriated by the keepers of inns and hostelries. This shows that people met at such places to settle accounts, a friendly drink being a tribute to "mine host." The Jerusalem and Lloyd's coffee-houses are noted in the history of trading companies; the latter especially. The checker-board on the doorpost of the tavern is about the last phase of the abacus, in Europe at least.

The checkers on the posts of an inn door are to be seen upon a house in disentombed Pompeii.

The tally system was also introduced into England at the Norman Conquest. This was not for calculating, but for keeping accounts. The name of the device came with it across the Channel, being derived from the French tailler, to cut, the tally-sticks being cut and notched with a knife. A squared stick of hazel or alder was prepared, and the money account was notched on the edge, small notches representing pence; larger, shillings; still larger, pounds. The stick was then split longitudinally, so as to leave notch-marks on each portion; one part was laid away in the exchequer strong room, the other was given to the creditor of the government. When the person came for payment, his portion of the stick was laid against that in possession of the exchequer, and if they tallied the claim was admitted, perhaps paid.

This system survived the introduction of Arabic numerals into England about 670 years. In 1826 the time came for the venerable system to abdicate in favor of the other Oriental method which had been asserting itself for so long. The pile of sticks, in companies, regiments, and brigades, that had by this time accumulated was something terrific. The question was, How to get rid of them? Prescriptive custom would prevent their being issued to the poor, or sold to bake the bread of the people, as the Alexandrian library heated the baths of that imperial city; so one fine day in 1834 they were to be privately burnt. A stove in the House of Lords was selected as a proper place for the incremation of another relic of the past; the wainscoting of the chamber protested by catching fire, the House of Lords set fire to the House of Commons, and both were burnt to the ground,—a grand funeral-pile.

The bakers insisted for some years in keeping tally-stick record of loaves purchased by their customers; some of us recollect it.

The oldest surviving treatises on mathematics are by the famous Alexandrians, Euclid, about B. C. 300; Ptolemy, A. D. 130; and Diophantus, A. D. 156.

Decimal fractions were invented 1482.

The first work on arithmetic published in England was by Tonstall, Bishop of London, 1522. The Italians had been in that field many years before.

(Architecture.) The crown member of the capital of a column. Ab′a-ka.

A fiber from which Manilla-rope is made. Ropes and cables of this material float in sea-water. Ab´a-mu′rus.

A buttress or second wall, built to strengthen another. Ab´ap-tis′ton.

(Surgical.) A trepan saw. Ab´at-jour′.

(Building.) A skylight, or aperture for the admission of light. Ab´at-voix′.

A sounding-board over a pulpit or rostrum. Ab′at-tis.

(Fortification.) An obstacle employed in military operations for delaying the approach of an enemy and keeping him under fire as long as possible. It is formed of trees or large limbs having the branches under two inches in diameter chopped off, the larger ones being sharpened and interlaced, and pointed toward the enemy. The butt ends are secured by pickets, and may be partially embedded in the earth to prevent them from being readily removed.


Abattis are usually placed in front of the ditch in field fortifications, but they may be placed in the ditch against the coantersearp; in the former case they should be protected from the enemy's fire by a small glacis.

In a wooded country an abattis is readily formed by felling the trees in such a way that their branches shall interlace, leaving the trunk connected to the stump by a portion not cut; the stump should be high enough to protect a man behind it.

A small parapet formed of logs and backed by earth may be thrown up in the rear of the abattis, which thus constitutes a very efficient and available means of defence.

The abattis is referred to by Herodotus, Thucydides, and Xenophon, and was a common military defence derived from savage life. An abattis of thorny shrubs or limbs is the usual defence of an African Kraal against predatory beasts. Abb.

(Weaving.) Yarn for the warp. Ab-dom′i-nal Sup-port′er.

A bandage for the compression of the relaxed abdominal walls, intended to assist the muscles in holding the viscera in place. The simplest are made of elastic rubber covered with silk or cotton; they encircle the body from the navel to the pubes. Others are made of two steel springs passing over the crests of the pelvic bones, with a small pad resting on either side of the spine, and a large frontal one; their position and action being similar to that of a person holding his abdomen with both hands. They are of various patterns and designs; are used in cases of obesity, before and after parturition, and sometimes in cases of umbilical hernia.

Abdominal Supporter.

Moody's Supporter, 1864, has a corset A, with lacings c d and air-bag B secured by elastic plates b to the stays. The pad acts as an elastic truss.

There are various forms, patented and otherwise. A-bee′.

(Fabric.) A woven stuff of wool and cotton made in Aleppo. A-beam′.

Opposite the center of the ship's side; as, "the wind is abeam." Ab´e-run′ca-tor.

A weeding-machine. A-bout´-sledge.

The largest hammer used by blacksmiths; wielded by the helper, turn-about with the smaller hammer of the blacksmith himself. A-bra´dant.

A material, generally in powder, for grinding. The term includes emery, sand, glass. and many other materials. Laps, glazers, ritles, paper, etc. are armed with abradants. See EMERY; and GRINDING AND POLISHING MATERIALS. A-breu-voir′.

(Architecture.) The mortar-joint or interstice between two voussoirs of an arch or the stones of a wall. A′brid.

A brushing-plate around a hole in which a pintle works. Ab-sorb′ing-well.

A well or shaft, dug, bored, or driven through a retentive stratum to allow surface or spring water to pass to a porous stratum below the former, so as to form an outlet for drainage.

Such wells are made at discretion in England, but in France are regarded with jealousy, and their use is only permitted after an examination and report by experts as to their possible effect upon watercourses, drainage or irrigation of other properties, etc.

In the United States they are but little used, and are not under public regulation.

Absorbing-wells are known as dead wells in the South of England; they are made in the gravel, the upper portion being close-steened work and the lower open-steened work. The bottom is unpaved, to allow the water to infiltrate. A-but′ting-joint.

(Carpentry.) A joint in which the fibers of one piece are perpendicular to those of the other.

(Machinery.) A joint in which the pieces meet at a right angle. A-but′ment.

A fixed point or surface, affording a relatively immovable object against which a body abuts or presses while resisting or moving in the contrary direction. See PIER; SKEWBACK.

Pier Abutment.

1. (Building.) A structure which receives the lateral thrust of an arch. The abutment may be a pier or wing walls forming a horizontal arch; or the arch may be continued to a piled or hewn foundation, which is then the abutment.

2. (Machinery.) A solid or stationary surface against which a fluid reacts.

a. The wedge which lifts the piston of one form of rotary steam-engine, and which forms a surface for the steam to react against as it presses the piston forward in its circular path.

b. The wedge block in a rotary pump, where the piston traverses an annular chamber.

Piled Abutment.

c. One of the cylinder heads of a steam-engine, receiving the back pressure of the steam which is made effective upon the piston.

3. (Carpentry.) The junction of two pieces of timber, where the grain of one is at a right angle to that of the other, or nearly so.

Movable Abutment.

4. (Fire-arms.) The block at the rear of the barrel of a fire-arm (especially a breech-loader), which receives the rearward force of the charge in firing.

Stationary Abutment.

It has the function of the breech-plug or breech-pin in the muzzle-loading fire-arm.

A similar term is applied to the corresponding portion in breech-loading cannon.

In Fig. 6, the abutment D is movable upon an axis so as to expose the rear of the bore for the insertion of the cartridge.

In Fig. 7, the abutment D is stationary, relatively to the stock, and the barrel slips away from the abutment to allow the insertion of the cartridge. The variations in the arrangement are very numerous, and the different devices form the subjects of numerous patents in the United States and foreign countries. See FIRE-ARM; BREECH-LOADING.

Suspension Bridge Abutment.

5. (Suspension Bridge.) The masonry or natural rock in and to which the ends of a suspension cable are anchored.

6. (Hydraulic Engineering.) A dam is in some sense an abutment, as it sustains the lateral thrust of water. See DAM. A-but′ment Arch.

An end arch of a bridge. A-can′tha-lus; A´can-tha′bo-lus.

An instrument for extracting thorns or splinters from a wound. Ac-cel′er-a′tor.

1. A light van used in England for conveying mails between post-offices and railwaystations, etc.

2. A cannon, with several powder chambers, whose charges are exploded consecutively, in order to give a constantly increasing rate of progression to the projectile as it passes along the bore. Ac′cent-ed Let′ters.

Vowels having signs above them (or below, in the case of the cedilla "ç") to indicate a specific pronunciation; as:—

(Surgical.) A bandage applied over the nose; so called from its likeness to the claw of a hawk. Ac-com´mo-da´tion Lad′der.

(Nautical.) A ladder suspended at the side of a vessel to facilitate the passage to and from the boats alongside.

Side ladders and stern ladders hang from these parts of a ship. Ac-cor′de-on.

A free-reed instrument introduced into England from Germany about 1828. The exterior form of this instrument is a parallelopiped. The action consists of a bank of vibrating reeds or tongues which are operated by the bellows. Keys open the air-ducts to the respective reeds as the bellows are expanded and contracted. Dampers are attached to the end, which is grasped by the left hand, while the other end is furnished with keys by which the notes are sounded by the fingers of the other hand.

The concertina is an improved form of the accordeon.

A common form of the accordeon is shown in the engraving, which affords three views:—

A general exterior view;

A sectional view in the plane of the key-board, and exhibiting the separate wind-cells;


A sectional view at right angles to the latter, and exhibiting the parts concerned in the course of the air,—damper, bellows, ducts, and cells.

a a is a rectangular box, the lower portion of which is of air-tight flexible material forming the bellows and wind-chest; c is a partition forming the top side of the wind-chest, and the lower surface of the large cell d, and the ten smaller cells e e. In the bottom of each cell are two apertures cut through the partition c; each of these apertures is covered on one side by a thin metallic plate, which has a long rectangular opening in which a free reed plays as the air passes through the opening when the bellows is in action, and the appropriate key is lifted See FREE REED.

On the side of each aperture, opposite to that occupied by the reed, is a flap or valve of thin leather, cemented by an edge to the partition c. The reeds of each cell are fixed one to the upper side of the partition and the other to the lower side; the reed above the partition is sounded when the bellows is extended, and that below the partition when the bellows is collapsed; the flap of leather, in each case, prevents the sounding of the reed when the wind goes in a direction contrary to that described.

The large cell d has also apertures, which are provided with reeds and valves at the respective ends of the apertures, as just described. The plates of these reeds have two or three tongues of greater size and lower tone, forming a base which chords with the other notes by which the air is played.

The tops of the cells e e d, or the partition c, are covered with buff leather, against which the under side of the cover i i slides when it is pushed into closed position.

In the cover, over each of the small cells, is a hole closed by a key k, and over the large cell d are two holes, one at each end, closed by the keys l l, which are moved simultaneously by the knob m. The valve n, at the bottom of the wind-chest, forms a damper by which the bellows may be extended or contracted, when required, without sounding a note.

Several notes may be sounded together, and, the reed of each small cell being different, the compass is equal, tones and semi-tones being counted, to the number of reeds.

The accordeon differs from the melodeon more in size and the mode of manipulation than in principle. The latter will be considered by itself, but may be stated to be of such size as to constitute a piece of standing furniture, having its keys in a bank, like a piano, and foot pedals for the generation of wind, by which the reeds are vibrated as the action of the keys opens the corresponding valves. The same instrument is known in England as the harmonium, and has been known at various times by the names of seraphine, æolophon, symphonium, etc.

FAAS, June 13, 1854, combines, with the diatonic scale of the large keys, two other scales, viz., one for producing all the intermediate notes or semi-tones, and the other founded upon the subdominant of the diatonic scale; both arranged so as to be fringed by a single set of small keys, to enable the performer to produce harmony in any key. The valves of the lower, or small; keys stop two series of apertures opening from the wind-chest below. The two series of apertures are alternately opened and closed by means of a wind-stop, with two rows of apertures arranged in alternate order. These are governed by levers jointed to the wind-stop and to one another.

A sounding-board gives strength and resonance to the tones, and allows space for the described arrangement of the valves.

FAAS, August 12, 1856. Immediately beneath the perforated board through whose openings the air enters, is a thin sliding board with corresponding apertures. By means of a handle the operator adjusts the position of the board so as to vary the strength of the tones by regulating the quantity of air admitted to the reeds. Double keys close the apertures of the base reeds, the smaller keys covering holes through the larger ones, by which arrangement an entire octave of base notes is produced.

ZIMMERMAN, July 10, 1866, has certain distinguishing keys between the consecutive octaves, which give the same tone in either inflating or compressing the wind-chest.

Pries's Accordeon.

PRIES, June 21, 1864. The accordeon is so constructed as to admit of its being played in any key, to accompany an orchestra; this is accomplished by arranging double keyboards, one on each side of the instrument, which admit the additional number of keys, conveniently arranged for the additional reeds necessary for the purpose. The keys in the respective banks of each end represent octaves, and the respective ends represent different chromatic scales.

The instrument is called by the inventor an orchestron, and the banks of keys are placed at an angle with the side, so as to present the keys more conveniently to the fingers of the performer. Ac-coup′le-ment.

(Carpentry.) A timber tie or brace. Ac-cou′ter-ments.

(Military.) The devices by which a soldier carries his arms, ammunition, etc. These vary in the different arms of the service, according to the exigencies of the case.

Those for infantry consist of a cartridge-box and plate, cartridge-box belt and plate, waist-belt and plate, gun-sling, bayonet-scabbard, and cap-pouch; to which, on a march, are added the knapsack, canteen, and haversack.

The infantry cartridge-box is made of black bridle-leather, with an outer flap which turns over, covering the top, and is fastened by a short strap to a brass button; inside of this is a lighter leathern cover to protect the ammunition when, as in action, the outer flap is necessarily left unfastened. A brass plate is generally affixed to the flap, but is not essential, being rather ornamental than useful. In the interior of the box are two tins, each having an upper and a lower compartment, the former being divided into two parts, one containing six and the other four loose cartridges, while a bundle of ten is placed in the lower compartment, which is open at the side; the box thus contains forty cartridges when filled. At the side is a small pocket, covered by a flap, for containing the implements, or "appendages," belonging to the musket, as the screw-driver and cone-wrench, wiper, ball-screw, spring-vice, and tumbler-punch.

Two loops are attached to the back for the passage of the cartridge-box belt, which passes diagonally across the body in front and rear from the left shoulder to the right side, where it passes beneath the waist-belt and is secured to the cartridge-box by two buckles. For ornament a round brass plate (in the United States service stamped with an eagle) is attached to this belt so as to fall about the centre of the chest of the wearer. The waist-belt, as its name imports, passes around the waist, and carries the bayonet-scabbard and cappouch; it also serves to keep the cartridge-box and belt in place close to the body; it is fastened by a brass plate of oval shape, having two studs and a hook, the studs entering two holes in one end of the belt, which is drawn tight and the hook inserted in a hole at the other end.

The bayonet-scabbard is made of black bridleleather; it is triangular in shape, to fit the bayonet, and has a brass ferrule at its bottom for ornament and protection; its length is 19 1/2 inches; a leather loop, or frog, is attached to the upper part of the scabbard for inserting the waist-belt.

The cap-pouch is also made of black bridle-leather, and has a flap and inner cover, the flap being fastened by a brass button; the pouch is 3 inches in length and depth, and is lined with sheep-skin with the wool on, to prevent the caps from being jarred out and lost when the flap is not buttoned. A conepick, of steel wire, bent so as to form a ring at one end, is inserted in a loop in one corner of the cappouch.

The gun-sling is of russet bag-leather, 1 1/4 inches wide and 46 inches long; it has a standing loop at one end and a brass hook at the other, with a sliding loop between. For use it is passed through the guard-bow and middle-band swivels of the musket, the hooked end passed through the loops and inserted in one of a series of holes punched in the sling; the gun may then be slung across the back, leaving both hands free, or it may be suspended from any suitable object.

All belts in the United States land service are black, and are made either of leather or of a strong species of felting, called buff, probably because belts were formerly made of that color.

Until within a very few years a separate belt was used for suspending the bayonet-scabbard, passing over the left shoulder and crossing the cartridge-box belt diagonally on the breast, which was ornamented with a plate at the crossing; the intersection of these two white lines, particularly when relieved against the dark-blue ground of the uniform, rendered the soldier as perfect a target as a marksman need desire, the plate representing the "bull's eye."

The cartridge-box belt has sometimes been dispensed with, particularly for riflemen, the whole weight of the accouterments, with, in this case, the addition of a heavy sword-bayonet and scabbard, being borne by the waist-belt, which of course had to be drawn very tight, forcibly compressing the abdomen, and causing great and unnecessary fatigue or even permanent injury.

This arrangement was, we believe, generally condemned by medical men, and in fact by every one who thought on the subject; but as the weapon above mentioned was in very limited use, toward the close of the war especially, the evil was not so general as it might have been.

The cartridge-box for cavalry resembles in external appearance that for the infantry, but is smaller, and its two loops are arranged so as to pass the saber-belt through them. Those used by our troops during the late war were variously arranged in the interior to suit the supposed necessities of the cartridges of each particular kind of carbine, as Burnside's, Merrill's, etc., etc. That adapted for a paper cartridge, as Sharp's, of which a greater number was issued than of any other, appeared to answer very well for others, though, no doubt, for metallic cartridges a special box is better.

The cavalryman is also provided with a small box or pouch for revolver cartridges and a cappouch.

The saber-belt, to which all the preceding are attached, consists of a waist-belt, with two brass rings for the shoulder-strap and saber-slings, and a brass loop sewed at one end to receive the plate, which is rectangular and connects the two ends of the belt together. The shoulder-strap passes from a ring on the left side over the right shoulder, and returns, supporting the saber, which is suspended by two saber-slings passing from the brass ring at the waist-belt through two iron rings on the saberscabbard, and buttoned.

The accouterments for horse artillery merely consist of a pistol cartridge-pouch and a cap-pouch, both similar to those above described, and a saberbelt which differs from the cavalry-belt only in the omission of the shoulder-strap.

A number of patents have been granted in the United States for improvements in the construction of, and in slinging accouterments. Since the commencement of the late war thirty-five patents have been granted in this branch of inventions. Attention has been directed to several points:—

First. The ease of the soldier in carrying his knapsack, etc. has been attempted to be secured: 1. By making one portion of his accouterments balance another, as in Mann's, Mizner's, and Wood's; 2. By a saddle-piece resting on the hips, as in Dickey's; 3. By suspension-hooks on the shoulders, as in Sweeney's; 4. By a frame reaching from the shoulders to the buttocks, as in Baxter's; 5. By modes of shifting the weight occasionally to vary the point of pressure and relieve the otherwise constant strain, as in Short's and Süs's.

Mann's Mode of slinging Accouterments.

Secondly. In arrangements for making the knapsack do service as a shelter, couch, or mattress.

Thirdly. In devices for the more compact arrangement of the compartments of the knapsack, haversack, or cartridge-box to increase their utility, readiness for duty, and lightness.

The accompanying cuts will render it unnecessary to give a lengthened description, and the examples are placed in the order stated, founded on the similarities of purpose and means.

MANN, December 8, 1863. The cartridge-box is worn in front of the person, and acts as a counterbalance to the other accouterments, the weight of the whole being thrown upon the shoulders.

Wood's Mode of slinging Accounterments.

WOOD, May 15, 1866. The devices refer to the means for slinging the gun, bayonet, cartridgebox, and canteen so as to counterpoise each other and the knapsack. The gun is hung to hooks on the strap. A hook on the cartridge-box adapts it to be attached to any part of the equipment. The bayonet is also slung by a hook on its scabbard.

When the accouterments are shifted to the rear, the hind side of the belt is connected to a ring beneath the knapsack, to help sustain the belt.

Mizner's Cavalry Accouterments.

MIZNER, January 16, 1866. The haversack, which is carried on the shoulders, forms a counterpoise for the cartridgeboxes, which are worn on the front of the belt; the upper portion of the divisional haversack is occupied by boxes, to contain three days' meat, coffee, sugar, and salt, in separate cases; the lower or bag-like portion being adapted to contain an equivalent quantity of bread. A strap passing along the bottom and up one end of the cartridge-box affords the means for elevating the packages of cartridges, which fit closely therein, and are difficult of removal by the fingers.

Dickey's Knapsack Supporter.

DICKEY, March 21, 1865. To relieve the soldier of the backward pulling of the knapsack it is partially supported by adjustable standards rising from a saddle-piece, which rests upon the hips.

SWEENEY, February 4, 1862. The knapsack is so suspended that an air space may intervene between it and the back of the soldier. The curved pads c rest upon the shoulder, and the bars B descend therefrom to the back plate D. The knapsack is secured by plates to these parts, and rigidly held at a distance from the back.

Sweeney's Knapsack.
Baxter's Knapsack Sling.

BAXTER, March 17, 1863. This improvement is intended to prevent the pressure of the knapsack upon the small of the back and the cramping of the movement of the arms, and it consists in supporting the sack by strips of wood extending from the shoulder to the hips; also in securing the chest-straps so as to leave the arms free.

Short's Knapsack.

SHORT, January 28, 1862; December 14, 1862. The mode of slinging the knapsack permits it to be loosened so as to fall away from the shoulders and spine of the wearer, as a means of shifting the weight and pressure, and allowing circulation of air against the back of the person. The arrangement also permits it to be raised or lowered in a vertical line according to the convenience of the soldier. The neck and shoulder strap is connected to the upper part of the knapsack by intermediate straps, and the lower part of the same is designed to prevent lateral swaying during quick movements.

Süs's Knapsack.

SÜS, May 17, 1864. This invention consists in the employment of a pair of suspending straps which pass over the shoulder in connection with another shorter pair of straps attached to the top of the knapsack near its center, and also a pair of straps attached, one to each end of the knapsack, for the purpose of varying the position and shifting the weight of the same when desirable.

Weber's Knapsack.

WEBER, January 31, 1865. The frame of the knapsack is capable of being changed into a couch, and the cover forms a shelter. The central section has jointed and folding sides.

Rush's Knapsack.

RUSH, March 25, 862. The frame of the knapsack is made of two parts, hinged together. At the thick end of one part are pivoted two arms, which, when thrown out, rest upon the edge of the knapsack, and serve to hold the canvas for forming a bed.

Frodsham and Levett's Knapsack.

FRODSHAM AND LEVETT, October 1, 1861. This invention consists of an india-rubber casing made water-tight and containing a bag of finely cut cork or other filling, thus forming a life-preserver. A pocket is made in the rubber casing to contain articles of clothing, thus forming a knapsack, which when unrolled becomes a bed, the contained articles forming a pillow.

MIZNER, November 27, 1866. The knapsack is combined with a haversack. The straps that secure the parts of the sack together, when packed and folded, are not sewed to the material, but are riveted to each other, and also to the sling-straps. The latter pass from the knapsack over the shoulders, beneath the armpits, and unite behind the back.

MCEVOY, January 7, 1862. The body is made of wicker-work, and has partitions and doors; it is covered with waterproof material, and contains medicines, lint, bandages, splints, and surgical instruments. It is designed to be carried by the surgeon's orderly in an engagement or during field duty.

Mizner's Knapsack.
McEvoy's Knapsack.

An india-rubber spring which accumulates lifting force, and is applied to many specific purposes on board ship, in machineshops, etc.


An apparatus used in working hydraulic cranes and other machines where a steady and powerful pressure of water is required. The accumulator is intended as a substitute for a natural head, as being more compact. Sir William Armstrong, in the first applications he made of this principle to hydraulic cranes, employed a natural head of water as the motive agent, obtaining the same by pumping water into tanks at an elevation of about 200 feet; but subsequently he has always employed the accumulator, as offering the advantages of greatly increased capacity for pressure, and a less prime cost of erection. The accumulator is shown in Fig. 24; it consists of the large cast-iron cylinder a, fitted with the plunger b, which works water-tight by means of the gland c, and packing. To this plunger is attached, by means of the bolts f, and strong cast-iron crosshead e, the loaded weight-case d. Thus a pressure is obtained upon the water in the cylinder, equal to a column of water 1500 feet high, or 660 lbs. upon the square inch. As the water is pumped into the cylinder by the pumping engines through the pipe h, the piston, with the weighted case, rises, being guided by the strong wooden framework g, and is made to regulate the amount of water pumped in, by actuating a throttle-valve in the steam-pipe of the pumping engine, which it closes after having reached a certain height. When the cranes, etc. are in operation, the water passes from this cylinder through the pipe i, to those actuating the motion of the cranes, and the weighted plunger naturally descends, always keeping up a constant pressure upon the water; in descending, the same causes the throttle-valve to open again, and the water is again pumped in. A′ces.

(Nautical.) Hooks for the chains. A-cet′i-fi-er.

An apparatus for exposing cider, wort, or other wash to the air to hasten the acetification of the fermented liquor. See GRADUATOR. Ac´e-tim′e-ter.

See ACIDIMETER. Ac´e-tom′e-ter.

A hydrometer suitably graduated for ascertaining the strength of acetic acid and vinegar. Ach´ro-mat′ic Con-dens′er.

An achromatic lens or combination used to concentrate rays upon an object in a microscope. See Carpenter on the Microscope, pp. 117–119, ed. 1857. Ach´ro-mat′ic Lens.

Achromatic, literally colorless, lenses were first introduced by John Dollond, of London, about the year 1758. Ever since the invention of the telescope it had been a desideratum with astronomers and opticians to obtain a lens which would give a perfect image free from color with a moderate focal length, it having been found by experience that it was necessary to increase the length of focus of the object-glasses of telescopes in the proportion of the square of the magnifying power desired, to obtain distinct vision. This was owing in part to the distortion or spherical aberration, caused by the rays striking the lens at greater or less distances from its center, being refracted at different angles in proportion to the greater or less convexity of the lens, and converging to different foci more or less distant from the latter; but principally to the dispersion or decomposition of the light, as in prisms, to two of which, joined at their bases, the lens is in fact equivalent. See PRISM.

This fringed or colored appearance may be observed about the margin of almost any object viewed through a lens of short focal length, such as an ordinary microscope.

The excessive length which had to be given to re- fracting telescopes in order to obtain what is now considered a very moderate magnifying power, 100 feet for a power of 200, led Gregory and Newton to the construction of reflecting telescopes (see TELESCOPE), and these for many years were almost the only kind in use. The dispersion of light, or the length of the spectrum formed by prisms having the same refracting angle, varies greatly in different substances though their refracting powers may be equal or nearly so.

Newton had supposed that the dispersion was always proportional to the refraction, and it was in the course of a series of experiments undertaken in order to verify this theory of Newton, which had been controverted, that Dollond was led to his discovery.

He found that a prism of white flint glass whose refracting angle was about 25 degrees refracted the light in a nearly equal degree with one of crown glass whose refracting angle was 29 degrees, but that the dispersive power of the former was much greater; so that, when they were applied together to refract contrary ways, a beam of light passed through them was separated into its component colors, although the incident and emergent parts of the beam continued parallel.

From this he inferred that if two lenses, one convex and the other concave,—which are in effect equivalent to two prisms refracting in different ways, —were so arranged as that the dispersive power of the flint glass would be corrected by the crown glass, that the image produced by the excess of refraction of the latter would be sufficiently colorless and distinct to bear an eye-glass of much shorter focal length and consequent magnifying power than could be applied to a non-achromatic, double-convex lens, formed of a single piece of glass; and by further experiment he ascertained the most advantageous focal lengths to be given to each glass in order to produce clearness and distinctness.

Achromatic Lenses.

He adopted a combination of three lenses, the middle one being of flint glass and double concave, and the two exterior ones of crown glass, double convex, believing that it produced better results and more effectually corrected the spherical aberration; the combination of two glasses is now, however, universally adopted.

It has been proposed to use metallic solutions and other liquids which have a higher dispersive power than flint glass, enclosed in glass disks of the proper curvature hermetically sealed at their edges, in place of that article for the concave lens, but though several of these substances appear to have given excellent results experimentally, they have never been brought into general use.

On account of the difficulty of obtaining a good article of flint glass, more particularly, and the trouble and skill required in grinding and polishing the faces of each piece so that they may have the proper curvature and fit accurately together, achromatic lenses have always been and will probably continue to be very expensive, especially the larger sizes. Dr. Dick mentions one of 5 1/2 inches aperture and 5 1/2 feet focal length, which cost 200 guineas.

Plöpl, an optician of Vienna, has recently invented an improvement on the achromatic, which he calls the dialytic telescope, in which the several different kinds of glass composing the compound object-glass are not placed close together, but at regulated distances apart. This arrangement allows a shortening of the tube.

Chester More Hall, of Essex, England, invented the achromatic telescope in 1729, but did not make it public. Dollond had to invent it over again. Ac´id-im´e-ter.

An instrument for determining the purity or strength of acids, founded on the principle that the strength of any sample of acid is proportionate to the quantity of alkali which it will neutralize, or the quantity of carbonic acid gas which it disengages from a carbonate of soda or potash. An accurate and economical apparatus for this purpose is proposed by Dr. Ure, as follows: a graduated glass cylinder, having a discharge tube and capable of containing 10,000 grains of distilled water, is attached by a flexible tube to a Florence flask containing a supersaturated solution of carbonate of soda or potash, in which is a test-tube containing a sufficient proportion of acid by weight to evolve carbonic acid gas equal in volume to the contents of the cylinder. Bicarbonate of soda is preferred, as one equivalent of any acid disengages from it two equivalents of carbonic acid gas, and the quantities of various acids required to evolve a volume of gas equal to 10,000 grains of distilled water are as follows:—
Anhydrous sulphuric acid,16.80 grains.
Oil of vitriol,20.58 grains
Anhydrous nitric acid,22.67 grains
Anhydrous hydrochloric acid,15.33 grains
Anhydrous acetic acid,21.42 grains
Crystallized citric acid,80.64 grains
Anhydrous tartaric acid,63.00 grains

By tilting the flask the test-tube is upset and the acid brought in contact with the alkaline solution, liberating the carbonic acid gas, which passes over into the cylinder, displacing a bulk of water equal to that of the gas evolved, the amount of which is shown by the graduations on the side of the cylinder. This indicates the strength of the acid. For example, if the water should be depressed to the mark 50 on the cylinder, it shows that the sample contains but fifty per cent of pure acid. This apparatus is the converse of the alkalimeter, which see. A-cis′cu-lis.

A small mason's pick, with a flat face and pointed peen. A-cock′bill.

1. The situation of the yards when they are topped up, at an angle with the deck.

2. The situation of an anchor when it hangs from the cat-head by the ring only. A-cou´me-ter.

An instrument invented by Itard for measuring the degree or extent of hearing. A-cous′tic In′stru-ments.

Instruments or apparatus pertaining to the ears, the perception, measurement, or projection of sound.

I. Those appertaining to the ear are,—1. Prosthetic. 2. For exploration. 3. For operation.

1. Of the prosthetic are the


Cane Trumpet.


Conversation Tube.

Ear; Artificial.

Ear of Dionysius.

Ear Trumpet.


Tympanum; Artificial.

2. Exploration.


Ear Speculum.


3. Operation.

Ear Spoon.

Ear Syringe.

Eustachian Tube Instrument.

Meatus Knife.

Organic Vibrator.

II. Instruments for making or conveying audible sounds.

(Not including those of a prosthetic nature cited in Class I.)

Acoustic Telegraph.

Air pipe.

Alarms. (Varieties; see ALARMS.)

Musical Instruments. (Varieties, see MUSICAL INSTRUMENTS.)

Speaking Trumpet.

Speaking Tube.

Steam Whistle.

III. Instruments for measuring the quality of sound, the extent of hearing, the number of vibrations in a given time, etc.







IV. Auscultation Instruments.





(See the above in their alphabetical order.) A-cous′tic Tel′e-graph.

A telegraph making audible instead of visual signals.

In this sense — the most general — every sounder may be included in the class, for it is capable of being, and is, used to convey information by an arrangement of repetitive blows and intervals.

The present common use of the Morse instrument brings it within this category, the signals being read by ear rather than by consulting the paper ribbon.

The speaking-tube may be considered another form, conducting a puff of air to the other end, where it operates a whistle, or the sound is recognizable as an audible expression.

Bright's (English Patent) is adapted to communicate phonetic signals. It consists of an axle having a magnet and double arm; the magnet, when acted upon by electro-magnetic coils, causes the axle to vibrate or deflect in one direction, thus sounding a bell by means of a hammer-head on one arm; the subsequent reversal of the electric current causes a muffler on the other arm to stop the sound.

In a more perfect form, Bright's Acoustic Telegraph consists of a hammer in connection with a lever, which is acted upon by every polarization of a set of electro-magnets by the local current, and thereupon strikes a small bell. A pair of these bells are connected to each wire; one bell is struck by the passage of the positive, and the other of the negative current, the alphabet being readily formed by the difference in their tones and the number of beats.

Another form of audible telegraph consists of a wire which is tapped and conducts the sound to a resonant diaphragm.

Wilson's Patents, 1866, refer to the production of a musical note by the action of a valve governed by the electro-magnetic current. The sound is continuous or intermittent, and variable in tone or pitch, as may be required. Ac′ro-ter.

A small pedestal placed on a pediment and serving to support a statue Ac-tin′o-graph.

An instrument for registering the variation of the chemical intensity of the sun's rays. As contrived by Mr. Hunt, it consists of a fixed cylinder on which is placed a prepared photographic paper covered by a revolving cylinder having a triangular opening divided by bars through which the direct rays of the sun pass; their effect upon the paper indicates their chemical intensity at different times. Ac´ti-nom′e-ter.

An instrument for measuring the power of the sun's rays, invented by Sir J. F. W. Herschel about 1825. A hollow cylinder of glass filled with a colored liquid is soldered to a thermometer-tube blown into a ball at the upper end; being exposed alternately to the sun's rays and removed to the shade, a comparison of the differences of expansion of the liquid indicates the relative intensity of the solar radiation.

The discovery of the presence of another principle, associated with the light and heat derived from the sun, seems to have been made some years ago by Mr. R. Hunt in England.

Sir J. Herschel proposed to establish, as a unit for the intensity of solar heat, that value which would. in a minute of time, dissolve a thickness equal to one-millionth part of a meter of a horizontal sheet of ice, when the sun's light falls vertically upon it. This he calls an actine, and from experiments made by him at the Cape of Good Hope he determined the value of a degree on the scale of one of his actinometers to be equivalent to 6.093 actines.

The actinometer is useful in determining the quantity of solar heat which is absorbed in passing through the different strata of the atmosphere, for which purpose the observations must be made at stations differently elevated above the level of the earth or sea. It may also be employed to determine the diminution of heat which takes place during eclipses of the sun.

See Manual of Scientific Inquiry, published by the English Board of Admiralty.

One form of actinometer is sometimes called a photometer. The former name indicates that its purpose is to determine the actinic power of the solar rays, while the latter name indicates a measurer of the intensity of the light.

One use of the actinometer is to ascertain the proper time for exposing a plate in the camera, or a sensitized paper in the printing-frame. The box has a spring bottom and a glass and wooden cover. On the under side of the glass are secured a series of thin strips of paper arranged in layers so that each layer projects over the edge of the strip above it, thus producing a graduated semi-transparent medium. The number of layers of any particular point is indicated by black figures on the lowest strips of paper. Upon this false bottom is spread a series of strips of paper rendered sensitive by saturating with alkaline chromate. The apparatus is then exposed to the light, and the strips of sensitive paper will be successively darkened according to the depth of over-lying paper. See PHOTOMETER. Ac′tion.

An exertion, applied in machinery to an effective motion; as, —

A single action; illustrated in the ordinary liftpump, the atmospheric engine, etc.

A double action, in which the go and return motions are each made effective or are positively effected by the motor: as the double-acting pump, throwing a stream at each course of the piston; the ordinary high-pressure steam-engine, in which the piston is driven each way by the force of stream.

(Music.) The movements or working parts of a stringed or wind instrument, which is operated by