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By heating, it exhibits positive electricity at one end, and negative at the other: as it cools, these electricities are reversed. It occurs in primitive rocks, chiefly in quartz and granite; with the former, it constitutes a peculiar mountain rock. It is found on many parts of the continent, and in Scotland. It differs from tourmaline in colour, degree of lustre, fracture, transparency, and distinct concretions; also in geognostic situations: tourmaline occurs almost always imbedded, and in single crystals; but schorl is aggregated,

and occurs in beds.

Tourmaline, called also electricus tur. malin, is of a green or brown colour, passing into others, even to the indigo blue. The colours are mostly dark. It occurs very seldom massive, oftener in rolled pieces, but most frequently crystallized. The crystals are generally threesided prisms; they are usually imbedded; the internal lustre is splendent and vitreous. It is hard, and easily frangible. Specific gravity from 3 08 to 3.36. Before the blow-pipe it melts into a greyishwhite vesicular enamel. It was found in Ceylon and the Brazils, in the 16th century; and since that in Madagascar and Ava, in many parts of the European continent, and in Scotland. Two specimens have been analyzed by Bergmann and Vauquelin, the former was brought from Ceylon, the latter from Brazil.

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Tourmaline has been long celebrated for its electrical effects, which are exhibited by friction, and also by heating: but if it is made very hot, as beyond 200° of Fahrenheit, it is deprived of its electrical properties. The more transparent the tourmaline, the stronger its electrical properties. It is sometimes cut and polished, and worn as a jewel; but on account of its want of transparency it is not very highly esteemed. The green coloured tourmaline has been described as the emerald; the blue, as the sapphire; and the crimson-red variety, first found in Siberia, and since in Ava and Ceylon, has been called the daurite, siberite, and rubellite. Mr. Greville is in possession of the most magnificent specimen of the red variety; it is valued, on account of its beauty and rarity, at 10002.

SCHOTIA, in botany, so named from Richard Vander Schot, a genus of the Decandria Monogynia class and order. Natural order of Lomentacex. Leguminosæ, Jussieu. Essential character: calyx five-cleft; petals five, inserted into the calyx, closed by the sides lying over each other; legume pedicelled There is but one species, viz. S. speciosa, lentiscusleaved schotia. It is a native of Senegal and the Cape of Good Hope.

viz.

SCHRADERA, in botany, so named in honour of Henr Adolph Schrader, a genus of the Hexandria Monogynia class and order. Essential character: calyx a superior rim, quite entire: corolla five or six cleft; stigmas two; berry one-celled, There are two species, many-seeded. capitata and S. cephalotes. SCHREBERA, in botany, a genus of the Diandria Monogynia class and order. Essential character: calyx two-lipped; corolla from five to seven-cleft; capsule pear-shaped, two-celled, two-valved; seeds from eight to ten, membranaceous winged. There is but one species, viz. S. swietenioides.

SCHWALBEA, in botany, so named in honour of Schwalbe, a physician, a genus of the Didynamia Angiospermia class and order. Natural order of Personatæ. Essential cha. Scrophularia, Jussieu. racter: calyx four-cleft, the upper lobe very small; the lowest very large and emarginate. There is but one species, viz. S. Americana.

SCHWENKFELDIA, in botany, so named in memory of Caspar Schenckfelt, a Silesian physician, a genus of the Pentandria Monogynia class and order. Natural order of Rubiaceæ. Essential character: involucre four-leaved; corolla

funnel-form; stigmas five; berry fivecelled, many-seeded. There are three species

SCHWENKIA, in botany, so named from Martin Wilhelm Schwencke, professor of botany at the Hague, a genus of the Diandria Monogynia class and order. Natural order of Luride. Scrophularia, Jussieu. Essential character: corolla almost equal, with the throat plaited and glandular; stamens three, barren; capsule two-celled, many-seeded. There is only one species, viz. S. Americana, Guinea Schwenkia.

SCIENA, in natural history, a genus of fishes of the order Thoracici. Generic character: head covered with scales; gill-membrane generally with about six rays; two dorsal fins placed in a furrow, into which they are often withdrawn. There are twenty-nine species, the principal of which is the S. cirrosa or bearded sciana, which inhabits the European and American seas, and is from one to two feet in length. It was known to the ancients, and esteemed by them for the table. It is of a pale yellow colour, striped longitudinally with dusky-blue. Its tail slightly lunated, and it has under its chin a short fleshy beard.

SCIAGRAPHY, the profile or vertical section of a building, used to show the

inside of it. The same term is used in astronomy, for the art of finding the hour of the day, or night, by the shadow of the sun, moon, stars, &c.

SCIENCE, in philosophy, denotes any doctrine deduced from self-evident and certain principles, by a regular demonstration. Sciences may be properly divid ed as follows: 1. The knowledge of things, their constitutions, properties, and operations; this, in a little more enlarged sense of the word, may be called Buon, or natural philosophy; the end of which is speculative truth. 2. The skill of rightly applying these powers, Talan; the most considerable under this head is ethics, which is the seeking out those rules and measures of human actions that lead to happiness, and the means to practise them; and the next is mechanics, or the application of the powers of natural agents to the uses of life. See PHILOSOPHY, moral. 3. The doctrine of signs, onustin; the most usual of which being words, it is aptly enough termed logic. See LOGIC.

This, says Mr. Locke, seems to be the most general, as well as natural, division of the objects of our understanding. For

a man can employ his thoughts about nothing but either the contemplation of things themselves, for the discovery of truth, or about the things in his own power, which are his actions, for the attainment of his own ends; or the signs the mind makes use of, both in the one and the other, and the right ordering of them for its clearer understanding All which three, viz. things, as they are in themselves knowable; actions, as they depend on us in order to happiness; and the right use of signs, in order to knowledge, being toto cælo different, they seem to be the three great provinces of the intellectual world, wholly separate and distinct one from another

SCILLA, in botany, squill, a genus of the Hexandria Monogynia class and order. Natural order of Coronariæ. Asphodeli, Jussieu. Essential character: corolla six-petalled, spreading, deciduous; filaments filiform. There are twenty-two species. The most remarkable is S. maritima, or sea onion, whose roots are used in medicine. Of this there are two sorts, one with a red, and the other with a white root: which are supposed to be accidental varieties, but the white are generally preferred for medicinal use. The roots are large, somewhat oval-shaped, composed of many coats lying over each other like onions; and at the bottom come out several fibres. From the middle of the root rise several shining leaves, which continue green all the winter, and decay in the spring. Then the flower-stalk comes out, which rises two feet high, and is naked half-way, terminating in a pyramidal thyrse of flowers, which are white, composed of six petals, and spread open like the points of a star. This grows naturally on the sea-shores, and in the ditches where the salt water naturally flows with the tide, in most of the warm parts of Europe, so cannot be propagated in gardens; the frost in winter always destroying the roots, and for want of salt water they do not thrive in summer. The root is very nauseous to the taste, intensely bitter, and so acrimonious, that it ulcerates the skin if much handled

SCIOPTIC, or SCIOPTRIC ball, a sphere, or globe of wood, with a circular hole or perforation, wherein a lens is placed. It is so fitted that, like the eye of an animal, it may be turned round every way, to be used in making experiments of the dar

kened room.

SCIRPUS, in botany, club rush, a genus of the Triandria Monogynia class and order. Natural order of Calamariæ.

Gyperoideæ. Jussieu. Essential character: glumes chaffy, imbricate every way: corolla none; seed one, beardless. There are sixty-nine species.

SCIRE facias, is a judicial writ, and properly lies after a year and a day after judgment given; whereby the sheriff is commanded to summon or give notice to the defendant, that he appear and show cause why the plaintiff should not have execution. A scire facias is deemed a judicial writ, and founded on some matter of record, as judgment recognizances, and letters patent, on which it lies, to enforce the execution of them, or to vacate or set them aside; and if execution is not taken out within a year, it is necessary to revive the judgment by scire facias. But if execution has isued within that time, a further writ of execution may be had without a scire facias. This writ is so far in nature of an original, that the defendant may plead to it, and it is in that respect considered as an action. Wherefore a release of all actions, or a release of all executions, is a good bar to a scire facias.

SCIRRHUS, in surgery and medicine, a hard tumour of any part of the body, void of pain, arising from the inspissation and induration of the fluids contained in a gland, though it may appear in any other part, especially in the fat, being one of the ways wherein an inflammation terminates. Lee SURGERY.

SCITAMINEÆ, in botany, the name of the eighth order in Linnæus's Fragments of a Natural Method, consisting of beautiful exotic plants, some of which, as the banana, furnish exquisite fruits, and others have a fine aromatic scent; among these are the amomum, or ginger; the canna, Indian flowering reed; and musa, the banana, or plantain tree. The plants of this order are all natives of very warm countries; they grow to great heights, but they are only perennial at the roots. Some of these plants are cultivated in high perfection at the botanical garden at Liverpool.

SCIURIS, in botany a genus of the Diandria Monogynia class and order. Essential character: corolla unequal, with the upper lip trifid, the lower bifid and shorter; stamina five, but three barren, capsule five, united, one-celled, oneseeded. There is only one species, viz. S. aromatica, found in the woods of Gui

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teeth in the upper jaw wedge-formed, in the lower sharp; five grinders in each side of the upper-jaw, and four in each of the lower; clavicles in the skeleton; tail spreading towards each side; long whiskers. These animals live principally on seeds and fruits. They are extremely ac tive and nimble, climbing trees with great rapidity, and bounding from one to another with a spring truly astonishing. Some are supplied with membranes, which enable them to extend this leap into something approximating to a short flight. Some are subterraneous, and others build in trees. They are sprightly, elegant, and interesting

S. maximus, or the great squirrel, is the largest known species, being equal in size to a cat. It is found in the East Indies, where it pierces the cocoa for the sake of the liquor, to which it is extremely attached. It is easily tamed.

S. vulgaris, or the common squirrel, abounds almost throughout Europe, and in the temperate climates of Asia. Its length is about seven inches to the tail, which measures about eight. During the summer's day, it generally remains in its nest, appearing to be annoyed by the heat; but at night it is full of alertness and vivacity, and devoted to excursion and repast. It constructs its nest generally in the fork of two branches of trees, and with particular precaution, with respect to dryness, warmth, and cleanliness. The young are produced sometimes about the beginning of summer, in general about the middle of it, and are three or four in number. Its food consists of various nuts and fruits, of which it stores considerable quantities for its winter consumption; it is fond also of certain species of fungi. In confinement it will take a vast variety of vegetable substances; but appears to prefer sugar to every other nourishment. See Mammalia, Plate XVIII. fig. 1.

S. cinereus, or the grey squirrel, is peculiar to North America, and is about the size of a half-grown rabbit. It resembles the former in its shape and manners. These animals have occasionally commited extreme ravages in some of the states of North America, in the cultivated lands; and to reduce their numbers, the legislature proclaimed a reward for their destruction. In the year 1750, a sum of no less than eight thousand pounds was distributed in premiums, to persons who had been engaged in killing them, and who must have destroyed between six and seven hundred thousand. It is not easily destroyed by the gun, on account

of the perpetual versatility of its movements, and some of the best marksmen are often baffled by this extreme agility. It is easily familiarized, and appears susceptible of affection and gratitude to its benefactors.

The S. variegatus, or varied squirrel, is nearly twice the size of the last, and differs also in habits, as it resides in holes under the roots of trees, where it produces its young, and, like the rest of the genus, accumulates its stores It is a na

tive of Mexico.

S. striatus, or the striped squirrel, is met with in the north of Asia and America, is subterraneous in its habitation, like the last, and is also addicted to hoarding, for winter, nuts and grain. It is distinguished, however, from every other species, by being provided with bags or pouches attached to its cheeks, in which, for the convenience of carriage, it can deposit large quantities of food, to take home with it after having swallowed a full meal. These squirrels abound in Siberia, amidst the woods of maple and fir, at the roots of which they make their burrows. They never mount trees, but when they have no other means of escape from an enemy, yet then they climb them with great celerity. They are very discriminating in their selection of food, and have been seen frequently to exchange cargoes contained in their pouches for a species of food which they casually and unexpectedly met with, and which they happened to prefer to the former. They retain in captivity much of their native wildness, and appear to evince no feelings of regard to their protectors.

S. volans, or the common flying squirrel, is the only one of that description in Europe, and is found there only in the coldest climates. In the north of Asia it occurs more frequently. Its colour above is a white grey, and beneath a perfect white. It is about six inches in length to the tail. It resides generally in hollow trees near the top, is solitary in its habits, associating even in pairs only in the spring. It feeds principally on the catkins of the birch, and in winter secludes itself in its nest, occasionally quitting it in fine weather. By means of an expansile furry membrane, reaching from the fore feet to the hind ones, these animals are enabled to spring or fly to the distance of thirty or forty yards. Climbing nearly to the top of one tree, it directs its movements always downwards, and by spreading this membrane as widely as

possible, with its fore feet extremely distant from each other, presents such a surface to the air beneath, as gives it considerable buoyancy, and converts its elastic bounds into a species of flight. The membrane is also highly serviceable in cherishing the young ones, which are produced usually in May, and about three at a birth. See Mammalia, Plate XVIII. fig. 4.

S petaurista, or the sailing squirrel, is an inhabitant of Java and the Indian Islands, and can spring to an immense dis. tance from tree to tree, by means of a membrane similar to that of the preceding, which is extremely thin in the middle, and thicker towards the extremities. This is the largest of all the flying squir rels, and is eighteen inches long, exclusively of the tail. For the Barbary squir rel and the black squirrel, see Mammalia, Plate XVIII, fig. 2. and 3.

SCLERANTHUS, in botany, knawel, a genus of the Decandria Digynia class and order Natural order of Caryophillei. Portulaceæ, Jussieu. Essential character: calyx one-leafed, inferior; corolla none; seeds two, inclosed in the calyx. There are three species.

SCLERIA, in botany; a genus of the Monoecia Triandria class and order. Essential character; male, calyx glume from two to six-valved, many-flowered, awnless; female, calyx from two to sixvalved, one-flowered, awnless; stigmas one to three; seed nut subglobular, somewhat bony, coloured. There are nine species.

SCLEROCARPUS, in botany, a genus of the Syngenesia Polygamia Frustranea class and order. Natural order of Discoideæ. Corymbiferæ, Jussieu. Essential character: calyx six-leaved, three exterior larger, like the leaves, three interior smaller, like scales, alternate; pappus none; receptacle chaffy. There is only one species, viz. S. Africanus, a native of the Cape of Good Hope.

SCLEROTICA, in anatomy, one of the tunics or coats of the eye; it is hard, opaque and extended from the cornea to the optic nerve; its forepart is transparent and is called the cornea.

SCOLEX, in natural history, a genus of the Vermes Intestina class and order: body gelatinous, variously shaped, broadish on the fore-part and pointed behind; sometimes linear and long, sometimes wrinkled and short, round, flexuous, or depressed: head protrusile, and retractile. Two species only are mentioned, viz. the pleuronectidis and Jophii; the former is found in the intestinal mucus of

the turbot, sole, plaise, gwiniard, and the lump fish, seldom visible to the naked eye. The other, as its name denotes, is discovered in the intestinal mucus of the lophus piscatorius: the body is minute, and hardly visible to the naked eye.

SCOLIA, in natural history, a genus of insects of the order Hymenoptera: mouth with a curved sharp mandible, crenate within; jaw compressed, project. ing, entire and horny; tongue inflected, trifid, very short; lip projecting, membranaceous at the tip and entire; four feelers, equal and filiform, in the middle of the lip; antennæ thick, filiform, the first joint longer. There are about twenty species.

SCOLOPAX, the curlew, in natural history, a genus of birds of the order Gralla. Generic character: the bill long and incurvated; face covered with feathers; nostrils linear and longitudinal near the base; tongue short and sharp-pointed; toes connected by a membrane to the first point. There are fifty species, of which the following are the chief: S. arquata, or the common curlew, is generally about two feet long, and is to be met with in England throughout the year, either on the coasts or near the mountains. Slugs and worms, which its bill extracts from the ground, in the morning and the evening, constitute its inland subsistence; and when on the shores of the sea it feeds on marine animals. These birds are often observed in large flocks, and are used by many for food. Those kill. ed on the coasts, however, are rank and fishy.

S. rusticola, or the woodcock. These birds are about fourteen inches in length. They are migratory in this country, and supposed to proceed from Sweden. They arrive about the beginning of October, but have never been observed on their first reaching land, and are supposed always to effect this by night or in misty weather. When first seen, they are extremely weak and exhausted, and have sometimes scarcely retained strength enough to fly to a very short distance, having been destroyed in numbers by a stick only. Before the rigours of winter set in, they reside in moory and mountainous districts; but in the extreme cold they change their haunts for such as are lower and warmer, and frequent particularly warm springs in glens and dells, covered with sheltering trees and brush. wood. They occasionally breed in this country, some few instances of this having been unquestionably authenticated;

VOL. XI.

but with such very extraordinary excep tions, woodcocks collect together about the middle of March, to return to their native country. They are often, however, like other voyagers, detained by unfavourable winds, and in such circumstances sportsmen find them in considerable numbers, and destroy them with unmerciful eagerness. The woodcock is more remarkable for stupidity than thtelligence, and is easily taken in traps and springes, which are placed for it near tepid springs, in passages artificially managed, as this bird never attempts to overcome obstacles in its way, even by leaping only off a small stone. It is, from this indolent tendency, decoyed into the direction, which, however smooth and pleasant at first, terminates in ruin. Its flesh is highly valued, but is considered as affording its full relish only when the bird is dressed entirely undrawn, in which state, with more epicurism than delicacy, it is generally eaten. See Aves, Plate XIII fig. 5.

S. gallinago, or the snipe, weighs about four ounces, is about twelve inches long, and to be found in nearly every country of the world. Its food consists of worms and insects, which it seeks near small streamlets, and in general in wet grounds. It eats also slugs. It is a bird of extreme caution and vigilance, and the sight of the sportsman or the dog impels it to immediate concealment amidst the dry herbage of its haunts, from which the resemblance of colour renders it almost impossible to discriminate it. On the approach of the enemy, it bursts from its shelter with such uncommon variety of direction and velocity of motion, as renders its destruction by the gun one of the greatest achievements of the sportman's art. Snipes are sometimes approached nearly, by the accurate mitation of their sounds, and shot upon the ground, and they are often taken by snares, like the woodcock. The fla vour and the preparation of them are also similar. They are in this country migratory, but cases have occurred of their breeding in it.

S. ægocephalus, or the common godwit, is of the weight of twelve ounces, and ranks in the highest order of delicacies. It is found in almost every country, and in the marshy grounds of Lincolnshire and Cambridgeshire is particularly abundant, feeding on insects and small worms, but approaches the sea shore on the advance of the rigours of winter. These birds, in several parts of the country, are

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