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ing from the latter into the tympanum is called the foramen rotundum; it is closed by a membrane to exclude the air of that cavity while it permits the transit of yibration to or from the vestibular perilymph within ; for that fluid, passing up the cochlea by the scala vestibuli, descends the scala tympani, and bathes the inner surface of the membrane of the fenestra rotunda. The o newel is kept in its place like the semicircular tubes by retiform filaments, and is supplied with a separate branch of the acoustic nerve, which ramifies and expands on its surface. The lapilli, which seem to be chiefly a provision for hearing under water, and are therefore large and solid in aquatic and am: phibious animals, appear in birds only as fine crystallized grains of chalk in the utricle, or sinus of the vestibule, rendering the endolymph somewhat turbid. The columella is straight, and the membrana tympani pressed outwards by it is consequently convex. There is a crescentic fold of skin extending upwards from the superior margin of the meatus externus, sometimes furnished, as in the horned owl, with a fringe of feathers which can be spread at pleasure like a fan to catch the sound. This fold of skin is a rudiment of the concha, or outer ear, of the mammalia. As we have already said, it is only in this last-mentioned class of animals that the ear reaches its complete development. It is nearly the same in all of them; the difference being only in the comparative size and shape of the oomponent parts of the organ, and not in their essential structure, number, or arrangement. We shall therefore describe the organ in one species only. There is every reason to suppose that in hearing, as in sight, man has no superiority over many of the lower aniInals, except what arises from that intellectual supremacy which enables him to discriminate and compare his sensations more justly than they can do. Indeed, it is certain that in the mere perception of sounds he is inferior to most of the mammalia, and probably to birds; and if the musical faculty should seem to imply a greater perfection of the organ, the error, for such we believe it to be, may perhaps disappear upon reflection. We therefore select the human ear as the type of the organ in mammalia, not because it is in any respect more complete than the rest, but as the most interesting. The same description, of the more important parts at least, might be applied, nearly word for word, to all. The parts now to be described fall naturally under a three-fold division into the internal, middle, and external ear. 1. The internal ear, comprising the acoustic nerve, vestibule, and labyrinth, is deeply placed in the interior of the head, within the most compact and hardest of the bones, denominated from that circumstance the petrous or rocky portion of the temporal bone. This wedge-like or triangular projection passes obliquely inward and forward in the direction of the outer tube of the ear, forming a strongly-marked knobby ridge within the cranium, in the basis or floor of that cavity. Near the inner point, which nearly meets its fellow on the other side, and upon its posterior declivity, there is a large trumpet-like hole (meatus auditorius internus) into which the seventh cerebral nerve enters from the medulla oblongata. [BRAIN, NERVE.] The meatus passes in a direction outwards, and therefore obliquely, into the petrous portion for half an inch, and then terminates abruptly in two foveae, or pits: from the upper of these goes a winding canal through the substance of the bone, which is the course of the motor nerve of the face (the portio dura of the seventh pair), which, here separating from the auditory nerve, or portio mollis, we need not follow. The latter, splitting into several sets of filaments, finds its way through small sieve-like openings at the bottom of the lower fovea into the internal ear, and is here distributed in three separate portions to the cochlea, the ampullae of the semicircular tubes, and the utricle, or vestibular sac. The cochlea is more complicated than in birds; it consists of a spiral canal in the bone, gradually diminishing as it ascends to a point, wound .# a central hollow pillar of bone, called the modiolus, or newel. From its inner surface, that, namely, which may be considered as a groove in the modiolus, a thin and spongy lamella of bone projects rather more than half across the canal, ascending in a similar spiral. From the edge of this lamella (called the lamina spiralis) a membrane passes to the outer surface of the canal, where it is attached; thus completing the separation of the canal into two scala, or winding partitions, which
while at the summit, and open (as before), the lower and
narrower into the vestibule, the superior and larger into the tympanum ; each scala taking two turns and a half round the modiolus in ascending from the base of the cochlea to the cupola, or inverted cup-shaped cavity at the summit, placed over the funnel (infundibulum) into which the top of the modiolus expands. The cochlea is on a level with the vestibule and anterior to it, the base being turned towards the meatus internus; the summit looking outwards and a little downwards, is turned towards the sudden bend of the wide canal in the petrous portion of the temporal bone by which the internal carotid artery enters the cavity of the head. It is the close neighbourhood of this artery as it passes through the compact bone that occasions the rushing sound of the pulse to be heard when the ear is placed upon a pillow, or d. attention is led to dwell upon what passes within, by deafness arising from some cause not affecting the parts essential to hearing. The modiolus is hollow to some distance from the base. Up this tubular cavity rises the large cochlear branch of the acoustic nerve, giving off lateral filaments through minute openings arranged spirally, which pass through the light spongy bone, and emerge from different points on the spiral floors and sides of the scalae, where they ramify in a delicate pulpy expansion upon the membranous tubes which line the spiral osseous canals: the rest of the cochlear nerve passes through capillary perforations in the cul-de-sac of the tubular cavity; and ascending in the substance of the central pillar of the modiolus, is distributed through the bone in a similar way to the upper turns of the cochlea and the infundibulum. The two other branches of the acoustic nerve are distributed to the vestibular sac, which lies in a round depression or pit in the barrel-shaped cavity of the vestibule, and to the ampullae of the semicircular tubes. The latter all meet in a membranous sinus, or utricle, which occupies another distinct pit of the vestibule, called, from its shape, the elliptic fovea, much according to the arrangement already described in other animals. The principal opening from the vestibule is the fenestra ovalis, situated on the outer side towards the tympanum, which is closed by a membrane; at the lower and front part there is another opening into the scala vestibuli of the cochlea. There are five at its posterior and outer side, which lead into the semicircular canals, of which the superior and posterior enter the vestibule by a common foramen. The sac and utricle each contain a cretaceous deposit, which, in some of the lower mammalia, has the consistence of soft chalk. The cochlea and semicircular canals, from their complexity, are termed the labyrinth. With respect to the object of their peculiar arrangement, not even a probable conjecture has been hazarded. Yet they appear with surprising uniformity in all the mammalia, and some of them, as we have seen, in the more numerous tribes of birds, reptiles, and fishes. The bony canals of the labyrinth and vestibule are stated to be invested within by a delicate periosteum, the surface of which towards the perilymph is thought to be of the nature of a serous membrane, and to secrete that fluid.
The deafness which arises from causes which oftect the fenestra ovalis, or the nerves and canals within the vestibule and labyrinth, is seldom or never cured; and it is unfortunately very common. There is a very eno Yo by which the nature of the case may be often sufficiently tested. If the internal ear be affected, especially the nerves of it, the ticking of a watch pressed against the teeth or the outer part of the head on that side, will be very obscurely distinguished. If not, the sound can be easily heard, as the solid bones interposed between the sonorous body and the nerve are excellent conductors of vibration. 2. The middle ear comprises the cavity of the tympatium. with its contents; the cells in the bony prominence behind the ear, called the mastoid process, with which the tympanum communicates; and the Eustachian tube, or passage jeading from the tympanum into the upper and back part of the throat, where it opens in the form of an expanded slit on each side behind the posterior nares. The tympanum is an irregular cavity scooped in the petrous portion of the temporal bone between the vestibule and the external meatus. The principal entrances to it are the fenestra ovalis and the round or somewhat oval opening at the bottom of the external passage upon which the membrana tympana is stretched. Between these there is extended a chain of three small bones, obliquely articulated to each other with perfect joints, so placed that the chain somewhat resembles in figure the letter Z. These bones are called respectively the stapes (stirrup), the incus (anvil), and malleus (hammer), from some similarity in form to those implements. The base of the stapes is applied to the fenestra ovalis, exactly fitting it, and is attached firmly to its membrane. The o of the Jonger leg of the incus is articulated to the head of the stapes, and there is a minute bone between them of the size of a small shot, which is generally considered to be only a process of the incus. It is however called from its spherical shape the os orbiculare, and is sometimes reckoned as a fourth bone. (Fig. 3, o.) The shorter leg of the incus (sig. 2, c,) rests against the bony parietes of the tympanum at the back part, near the mastoid cells. Upon the hollowed cavity in the head of the incus (fig. 2, a) the lateral depression of the head of the malleus (fig. 2, k) is articulated, and moves easily; the long handle of the latter is attached by its extremity (fig. 2, h) to the middle of the membrana tympani, as well as by a portion of the side of the handle, which lies close to and parallel with the membrane. The long slender process of the malleus called the processus gra: cilis (fig. 2. g) lies in a slit passing to the articulation of the jaw called the glenoid fissure.
most reptiles; this is to permit the membrana tympani to be drawn into a conical shape so as to tighten it, and adapt it either to resist the impulse of too loud a sound, or favour a more acute or gentle one. The muscle which chiefly effects this object, called the tensor tympani (sig. 4, a), is attached near the head of the malleus to a point projecting from it. (Fig. 2, f.) Other muscles, to steady and antagonize its action, called the larator major and minor tympani are also attached to the malleus, the former (sig. 4, b) to the processus gracilis, the latter (sig. 4, c) to the handle of
the bone. A further description of the directions and outer attachments of these minute muscles would be tedious and unintelligible to the general reader. No muscle is attached to the incus, but a small one of great importance is inserted into the neck of the stapes, called the stapideus; the effect of this is to counteract the obliquity of traction or tilting of the stapes, which would otherwise ensue from the movements of the other bones; by this means the motion of the stapes is directed either immediately to or from the fenestra ovalis, the membrane of which is also further preserved from injury by the oblique arrangement of the joints of these minute bones, by means of which, although the membrane of the tympanum oscillates through a considerable space in passing from tension to relaxation, that of the fenestra is moved to a much smaller extent. It is to be observed that the same action which draws the membrana tympani into a come thrusts the base of the stapes farther into the fenestra ovalis. These small muscles are not under the dominion of the will, being supplied with nerves in a way peculiarly interesting to a physiologist, and acting automatically in correspondence with the impressions on the auditory nerve. Yet the instinctive consciousness we have of the degree of their contractions in adjusting the tension of the membrana tympani to circumstances, is probably one of our chief means of estimating the intensity of sounds. The fenestra ovalis is situated nearly opposite the membrana tympani, on the upper edge of a prominence called the promontory; it faces outwards and a little downwards; and beneath it, concealed by the promontory, is the foramen rotundum, closed by a membrane, and leading into the cochlea by the scala tympani. The object of this last opening is disputed: some think it conveys in part the vibrations of the air of the tympanum to the internal ear; but it seems more reasonable to suppose, with Sir C. Bell, that the end it chiefly serves is to give vent and freedom to those of the fluids pent up in the unyielding bony canals of the labyrinth. Besides these openings from the tympanum, there are others which lead into the mastoid cells behind it; these are also filled with air, and are supposed to contribute to the distinctness of the tympanic vibrations. There is also an opening from the tympanum forwards into the Eustachian tube. This canal is nearly two inches long the first part of its course from the tympanum is bony: it then becomes cartilaginous, and widens as it approaches the throat, the mucous membrane of which lines it, and thence passing into the tympanum, spreads over the surface of the whole cavity, investing the ossicula and its other contents, as well as the mastoid cells. From this circumstance arises the tendency of the inflammation of cold or sore throat to extend into the tympanum, producing temporary deafness, ear-ache, and sometimes mischief of a more permanent kind. From the deafness which accompanies the closure of the Eustachian tube by that or other causes, the importance of its functions in renewing and giving vent to the air within the tympanum may be appreciated. Besides the foramina already mentioned, there are others through which nerves and vessels enter the tympanum. We have not space to describe them: we shall only mention that one of the nerves, called the chorda tympani, originally connected with the
portio dura of the seventh nerve, after traversing the petrous
bone in a circuitous course, enters the cavity of the tympanum, and passing quite across it, is transmitted through the glenoid fissure to a salivary gland under the lower jaw. The object of this singular but uniform course of the chorda tympani is not well understood. Deafness arising from closure of the Eustachian tube has been sometimes cured by dilating that canal by in: struments passed for that purpose into its outer expanded extremity through the nostrils, or from the back of the throat; or by injecting fluids into it by means of a syringe with a small curved pipe. This latter plan has also been successful in curing deafness arising from chronic inflammation, or morbid secretion within the tympanum. Suppuration within that cavity, or in the mastoid cells, sometimes results from high inflammation, and has been attended with fatal consequences by spreading to the bones of the cranium, or along the nerves to the brain, or its membranes. Cases of this kind generally originate, as we have already stated, in cold with sore throat, and are found to occur chiefly in scrofulous habits.
Fig. 5. This is not to be considered as a correct delineation of the organ, being intended only as a diagram, to give a general idea of the relative situations of the several parts. a, superior semi-circular canal; b, posterior ditto ; c, external ditto; d, scala tympani of the cochlea opened, to show r, the fenestra rotunda, entering the tympanum under the promontory; e, Bustachian tube; f, membrana tympani; g, vestibule, not laid open 5 m, meatus auditorius externus; m, meatus internus, terminating in twofovea,
3. The external ear consists of the meatus auditorius earternus (fig. 5, m) and concha. The former, commencing from the membrana tympani, is an osseous canal in the first part of its course in the adult, and then becomes nothing more than a tubular continuation of the expanded cartilage of the concha, or outer appendage of the ear. It is lined throughout with a delicate skin, covered by thin cuticle, which also covers the outer surface of the membrane. Beneath the skin, and opening through it on the surface, are numerous landular follicles which secrete the ear-wax or cerumen. #. the foetus and new-born infant there is hardly any appearance of this tube; the membrane of the tympanum being close to the surface of the head, stretched upon the inner margin of a bony ring (annulus auditorius) which afterwards increases in length and becomes a tube. In the adult the length of the whole tube may be nearly an inch; but from the obliquity of the membrane, which faces a little downwards, it is longer below than above. Its direction from the membrane is outwards and a little backwards, and it is slightly convex upwards, and rather narrower in the middle than elsewhere. The last mentioned peculiarity is the reason why it is so much easier to introduce beads and other round bodies (as children are apt to do) than to get them out. This however must always be done as soon as possible when such an accident happens; for the presence of the foreign body sometimes excites great inflammation and swelling, and may lead to very serious consequences. The most easy method and the least painful is to direct a stron stream of warm water into the tube with a syringe, whic commonly succeeds immediately if resorted to before there is much swelling. Other means will readily suggest themselves; but if resorted to, they should be very tenderly used, for the part is extremely sensitive, especially the membrane itself, to rough contact. The wax, which is very bitter, P. C., No. 561.
serves to prevent the entrance of insects and to keep the skin soft. When secreted too abundantly, it is often a cause of deafness, and should be removed as a foreign body by means of a syringe and a solution of soap in warm water. The commonest kind of ear-ache is that caused by inflammation of this passage, and is generally followed by a copious and foetid secretion poured out by the ceruminous follicles. If this last long, deafness is sometimes the result from thickening of the membrane, and has been removed, as well as that arising from closure of the Eustachian tube, by puncturing the membrane. This part is sometimes ruptured by the spasmodic action of the tensor muscle caused by loud sounds, or by driving air up the Eustachian tube in a forcible expiration, as in blowing the nose violently. This accident is not followed by the degree of deafness that might be expected, unless the stapes becomes displaced from the fenestra ovalis: the other ossicula may be lost with comparative impunity for obvious reasons.
Fig. 6. View of the pinna, or auricle. The cartilaginous prominences are, a, helix; b, anti-helix; d, tragus; e, anti-tragus: the lobe or lobulus, g, contains no cartilage, beiug composed 3. of skin and a salty cellular tissue. The depressions are c, the scapha or scaphoid (boat-like) fossa; and f, the concha, a term often used to denote the whole appendage of which it is the most important part. The concha, or pinna, or auricle (for by all these names the outer appendage of the ear is known), consists of several pieces of elastic cartilage expanded in a form more or less resembling an ear-trumpet in different animals. In man it serves the purpose of collecting the sonorous vibrations and directing them into the meatus externus much less perfectly than in many other animals, which are also provided with muscles for directing it to the source of sound, which in man are but rudimentary. It is marked with various prominences and hollows, of which the names are given in the figure. It does not seem necessary to describe them more particularly. The cartilages are bound by ligaments to the neighbouring prominences of bone, and are covered by a smooth and closely adherent skin. It may be observed that the aquatic mammalia (whales, porpoises, &c.) are unprovided with this part of the organ; and have a very narrow but long and curved meatus externus, passing obliquely into the surface of the head, and in some instances capable of being closed by a flap of movable skin to exclude the water. In these animals also the cochlea is imperfect, the scalao making but one turn and a half round the modiolus.
(Scarpa, de Auditu; Soemmering, ditto; Breschet, ditto; Hole. Comp. Anat.; Bell's Anatomy; Grant's Outines.)
EAR-RING; a ring hung from a hole, perforated for that purpose through the ear, sometimes set with pendant jewels, pearls, or other precious stones. The word is Anglo-Saxon, ear-hring. Ornaments of this sort, large or small, have been worn in almost all countries by women, from the earliest ages; but more rarely by the men. , Montfaucon says that the men, in many instances, wore them as amu; lets. In the Latin of the middle age ear-rings are termed pendentes, from the more common form of the,onents usually attached to the ring itself. Sir Richard Hoare, in his antient Wiltshire, describes the ear-rings of a British female found in one of the barrows of that only.
EARL.” The title of count or earl, in Latin comes, is the most antient and widely spread of the subordinate or subject titles. This dignity exists under various names in almost every country in Europe. By the English it is called earl, a name derived to us from the ealderman of the Anglo-Saxons and the eorle of the Danes. By the French it is called comte, by the Spaniards conde, and by the Germans graf, under which generic title are included several distinct degrees of rank,--landgraves, or counts of provinces, palsgraves, or counts palatine, of which there are two sorts, markgraves, or counts of marches, or frontiers, (whence marchio, or marquess), burghgraves, or counts of cities, counts of the empire, counts of territories, and several others. [Count : BARon.] As to the English earls, after the battle of Hastings, William the Conqueror, as it is well known, recompensed his followers with grants of the lands of the Saxon nobles who had fallen in the battle, to be held of himself as strict feuds; and having annexed the feudal title of earl to the counties of the Saxon earls (with whom the title was only official), he granted them to his principal captains, These earldoms were of three kinds, all of which were by tenure. The first and highest was where the dignity was annexed to the seisin or possession of a whole county, with “jura regalia.” In this case the county became a county palatine, or principality, and the person created earl of it acquired royal jurisdiction and seigniory. . In short, a county palatine was a perfect feudal kingdom in itself, but held of a superior lord. The counties of Chester, Pembroke, Hexham, and Lancaster, and the bishopric of IJurham, have, at different times, been made counties palatine; but it does not appear that the title of earl palatine was given to the most antient and distinguish'd of them, viz., the earl of Chester, before the time of Henry II, surnamed Fitz-Empress, when the title of palatine was probably introduced from the empire. The earls of Chester created barons and held parliaments, and had their justiciaries, chancellors, and barons of their exchequer. This county palatine reverted to the crown in the reign of Henry III. The second kind of earls were those whom the king created earls of a county, with civil and criminal jurisdiction, with a grant of the third part of the profits of the county court, but without giving them actual seisin of the county. The third kind was where the king erected a large tract of land into a county, and granted it with civil and criminal jurisdiction to be held per servitium unius comitatiis. Under the early Norman kings, all earls, as well as barons, held their titles by the tenure of their counties and baronies; and the grant, or even purchase, with the licence of the sovereign of an earldom or a barony, would confer the title on the grantee or purchaser; but with the solitary exception of the earldom of Arundel, earldoms, by tenure have long since disappeared, and in late times the title has been conferred by letters patent under the great seal. Earls have now no local jurisdiction, power or revenue, as a consequence of their title, which is no longer confined to the names of counties or even of places; for several earls, as Earl Spencer, Earl Grey, and others, have chosen their own names, instead of local titles. The coronet of an English earl is of gold surmounted with pearls, which are placed at the extremity of raised points or rays, placed alternately with foliage. The form of their creation, which has latterly been superseded by the creation by letters patent, was by the king's girding on the sword of the intended earl, and placing his cap and coronet on his head and his mantle on his shoulders. The king styles all earls, as well as the other ranks of the higher nobility or peerage, his cousins. An earl is entitled right honourable, and takes precedence next after marquesses, and before all viscounts and barons. When a marquess has an earldom, his eldest son is called earl by courtesy; but notwithstanding this titular rank, he is only a commoner, unless he be summoned to the House of Lords by such title. So the eldest sons of dukes are called earls where their fathers have an earldom but no marquisate, as the duke of Norfolk, &c. EARL MARSHAL OF ENGLAND, one of the great officers of state, who marshals and orders all great ceremonials, takes cognizance of all matters relating to honour, arms, and pedigree, and directs the proclamation of peace and war. The curia militaris, or court of chivalry, was formerly under his jurisdiction, and he is still the head of
the heralds' office, or college of arms. Till the reign of Richard II., the possessors of this office were styled simply Marshals of England: the title of Earl Marshal was bestowed by that king in 1386 on Thomas Lord Mowbray, Earl of Nottingham. The office is now hereditary in the family of Howard, and is enjoyed by the duke of Norfolk. (Chamberlaine's State of England. Dallaway's Inj into the Origin and Progress of Heraldry in ngland, 4to., Glouc. 1793, pp. 93-95.) EARSHELL. [HALIoTIDAE.] EARTH (Astronomy). In the language of astronomers, the earth is rarely treated as a planet. All the phenomena connected with its motion are seen in the apparent motion of the SUN, to which article we therefore refer. EARTH, CONTROVERSY ON THE MOTION OF THE. [Motion of THE EARTH.] EARTH, DENSITY OF THE. The fundamental experiment of Cavendish for the determination of this astronomical element being likely to be shortly repeated, it is advisable to defer this article: see therefore WEIGHT OF THE EARTH. EARTH, FIGURE OF THE. [Geodesy.] EARTH. The old chemists imagined that all material substances were ultimately resolvable into four simple bodies, viz. air, fire, water, and earth, which were therefore called the four elements. This term is still occasionally employed in a more restricted sense, as when mention is made of earthy salts, &c. It is now universally admitted, that the bodies called earths are compounds of oxygen and a base, and in fact that they are mostly metallic oxides. The principal earths are alumina [ALUMINUM), barytes [BARIUM), glucina [GLUCINUM), lime [CAlcium], magnesia [MAGNESIUM), silica [SILICIUM), strontia [STRoNTIUM), yttria [YTTRIUM), zirconia [ZIRconIUM). EARTH-NUTS are either the fruit of certain plants which bury it below the ground after the flowering is past, as the Arachis hypogaea, Lathyrus amphicarpos, and others, or else the subterranean tubercles of fleshy-rooted plants, such as Bulbocastanum, Cyclamen, Lathyrus tube
r0SuS, # tuberosa, and the like. EARTHENWARE. The art of moulding earthen vessels for domestic use appears to have been practised in the earliest ages, and undoubtedly has been known among the rudest nations. The most antient records allude to the potter's wheel, and we have proof that great skill had been acquired in, the manufacture of porcelain of a superior quality in China and in Japan at a very remote date. The little figures, covered with a fine deep-blue glaze, which are deposited with Egyptian mummies, and numerous jars, some specimens of which may be seen in the British Museum, show that in Egypt likewise the art was antiently practised; and indeed we see in Egyptian paintings representations of vessels (presumed to be earthen) which closely resemble those made in Egypt at present, and also the representations of the manufacturing process itself. (Library of Entertaining Knowledge, Egypt, ii. 179.) [Coolersj It has been supposed that the Britons understood the potter's art before the Roman occupation of this island, since urns of earthenware have been found in barrows in different parts of the kingdom; but other writers affirm, though we believe without proof, that our ancestors were in those days supplied with such articles by the Phoenicians. Vestiges of considerable Roman potteries have been discovered in many, parts of this island, particularly in Staffordshire; and there is an interesting account by Governor Pownai (Archaeologia, 5th vol., p. 282, &c.) of the discovery of numerous vessels of pottery which were fished up in the Queen's Channel, near Margate. It was for some time supo that a Roman trading vessel, freighted with pottery, had been wrecked at this place; but on a more particular examination of the spot, called by the fishermen Puddingpan Sand, Roman bricks cemented together, apparently the ruins of a building, were likewise discovered, and on farther investigation it was found that an island existed formerly on this spot on which there had been a large pottery established by the Romans. Many of the earthen pans were recovered in a perfect state, and several of them had the name of Attilianus neatly impressed upon them. The island has long since disappeared, but specimens of the manufacture carried on there were frequently drawn up during the last century in the nets of the Kentish fishermen. In newly-discovered countries it has been found that the
use of earthen vessels is familiar among people otherwise little acquainted with the arts of civilized life. Vases have been found among the aboriginal Indians on the Mosquito shore which were preserved as memorials of antiquity; and there is strong evidence for believing that these vessels were the manufacture of the country in which they were found, since the remains of antient potteries have been discovered at a considerable distance up the Black River on that coast. In the United States of North America also fragments of pottery made by the native Indians have often been discovered. Although earthenware may be considered as a general term applicable to all utensils composed of earthen materials, it is usual to distinguish such utensils more particularly into three different kinds; namely,–pottery, earthenware, and porcelain. Under the first of these terms are classed the brown stone-ware made into jugs, &c., the red pans and pots in common use, porous vessels, &c. [Pottery.] Porcelain is distinguished from earthenware as being a semi-vitrified compound, in which one portion remains infusible at the greatest heat to which it can be exposed, while the other portion vitrifies at a certain heat, and thus intimately combines with and envelops the infusible part, producing a smooth, compact, shining, and semi-transparent substance, well known as the characteristic of true porcelain. [PorcelAIN.] At present our notice will be confined to earthenware as used in its distinctive meaning. Until the beginning of the eighteenth century the manufacture of earthen wore in this country was confined to a few objects of the coarsest description, and till nearly the close of the same century, the porcelain of China was still in common use on the tables of the wealthy, the home manufacture being confined to articles of the commonest domestic use. Earthenware was likewise largely imported from Holland, and superior kinds from Germany and France. English earthenware and porcelain are now not only brought into general use in this country, to the exclusion of all foreign goods, but earthenware is also largely exported to almost every part of the known world, and even to those countries where the art was previously prosecuted. M. Faujas de Saint Fond observes on this subject—‘Its excellent workmanship, its solidity, the advantage which it possesses of sustaining the action of fire, its fine glaze impenetrable to acids, the beauty and convenience of its form, and the cheapness of its price, have given rise to a commerce so active and so universal, that in travelling from Paris to Petersburg, from Amsterdam to the furthest part of Sweden, and from Dunkirk to the extremity of the south of France, one is served at every inn upon English ware. Spain, Portugal, and Italy are supplied with it; and vessels are loaded with it for the East Indies, the West Indies, and the continent of America.' England is mainly indebted to Mr. Wedgwood for the extraordinary improvement and rapid extension of this branch of industry. Before his time our potteries produced only inferior fabrics, easily broken or injured, and totally devoid of taste as to form and ornaments. edgwood's success was not the result of any fortunate discovery accidentally made, but was due to patient investigation and unremitting efforts. He called upon a higher class of men than had usually been employed in this manufacture to assist in his labours, and in prosecuting his experiments he was guided by sound scientific principles. The early and signal success which crowned his first exertions only served as an additional motive for continuing his pursuit. One of the principal inventions of Mr. Wedgwood was his table ware, known at present as queen's ware, in consequence of the patronage of the queen, who commanded it to be thus designated. It is characterised as a dense and durable substance, covered with a brilliant glaze, and capable of bearing uninjured sudden alternations of heat and cold. . From its first introduction, it was manufactured at so cheap a rate as to render it an article within the reach of all. Soon after, embellishments were introduced which yery little enhanced the cost of the article; first, a coloured edge, or painted border was added to the queen's Ware, and, lastly, printed patterns covering the whole surface, which at first exhibited very little taste, but by degrees reached the perfection which the art has now attained. Mr. Wedgwood's more beautiful inventions were-a terra cotta, which could be made to resemble porphyry, granite, Egyptian pebble, and other beautiful stones of the silicious or crystalline kind: a black porcelainous biscuit, very much resembling basalt in its properties, and therefore called ba
saltes; a white and e-cane-coloured porcelain biscuit, both smooth and of a wax-like appearance; and another white porcelainous biscuit, distinguished as jasper, having in general all the properties of the basaltes, with a very important addition, the capability of receiving through its whole substance from the admixture of metallic oxides, the same colours as those oxides communicate to glass or enamel in fusion. This peculiar property renders it applicable to the production of cameos and all subjects required to be shown in bas-relief, as the ground can be made of any colour while the raised figures are of the purest white. Mr. Wedgwood likewise invented a porcelain biscuit nearly as hard as agate, which will resist the action of all corrosive substances, and is consequently pecularly well adapted for mortars in the chemist's laboratory. The principal ingredients employed in the composition of all kinds of pottery are clay and flint. The nature of the clay used in the manufacture is of great importance, and so also is the combining of it with a due proportion of flint. The clay principally used in the English potteries is obtained from Dorsetshire and Devonshire; that from the former county is brought from the Isle of Purbeck, and is considered superior to the Devonshire clay. It is of two kinds, distinguished as brown clay and blue clay. The clay from Devonshire is likewise of two distinct qualities, and known as black clay and cracking clay. All these clays are of good working quality, and burn extremely white, being free from any impregnation of iron: the blue clay is considered the best. Another description of clay, superior to either of the former, was first discovered in Cornwall by Mr. Cookworthy, in 1768, and is commonly denominated China clay, because similar in its properties to the porcelain earth of China. It is very white and unctuous, and on investigation has been found to be formed by the gradual disintegration of the felspar of granite. This Cornwall clay is prepared on the spot where it occurs. The partially decomposed granite is broken into small pieces, and thrown into a running stream, where the argillaceous parts are washed off and held suspended in the water, while the mica and quartz being heavier remain at the bottom. At the end of the stream the water is stopped by a dam, and the pure clay gradually subsides. . When the whole has separated itself from the water, the latter is drawn off and the solid matter dug out in blocks, which are placed in a situation exposed to a free current of air, and when sufficiently dry are packed in casks for shipment in the state of a fine smooth white powder. Mr. Wedgwood found by analysis that this substance contains sixty, parts of alumina and twenty parts of silica; it is infusible,” and remains unaltered in the greatest heat of a porcelain furnace. The price of this material is much higher than that of the other English clay; but in the making of porcelain it is indispensable, and it is also used in some of the finer kinds of earthenware. Preparation.—In the preparation of the clay some labour is required, before it is in a fit state to be combined with the flint. It is first mixed with very pure water to the consistence of cream: this work is called blunging, and in large establishments is performed by means of machinery. The result is a smooth pulp, which is then passed through a series of sieves of increasing degrees of fineness, till at length it is perfectly fitted to enter into the composition of the
ware. If the clay were moulded and dried without the ad.
dition of any other body it would certainly crack, as the evaporation of the water with which it is mixed, in order to render it sufficiently plastic for the potter's wheel, would cause it to shrink in the proportion of one part in twelve in drying. In combination with silicious earth in proper proportions, it bears the action of fire without cracking, while the silica materially improves the whiteness of the ware. The flints are prepared by being burnt in a kiln, and removed while red-hot from the kiln and thrown into cold water. By this operation their attraction of aggregation is lessened, and the labour of grinding them is much facilitated. They are then broken and ground to a very fine powder in a mill constructed for the purpose, the original of which was invented by Brindley. A quantity of water is thrown into the mill with the flints, by which the process is quickened and the health of the workmen is preserved, the finer particles of flint being thus prevented from flying off and mixing with the atmosphere which the workmen inhale.