preserved for several months, almost without coagulating, and proves a store of provision to the animal. The nutritious parts, pure and already digested by animals, have no call to be disengaged from the heterogeneous substances: nor indeed is there an anus discoverable in the leech; mere transpiration seems to be all that it performs, the matter fixing on the surface of its body, and afterwards coming off in small threads. Of this an experiment may be tried, by putting a leech into oil, where it keeps alive for several days: upon being taken out, and put into water, there appears to loosen from its body, a kind of slough, shaped like the creature's body. The organ of respiration, though unascertained, seems to be situated in the mouth; for if, like an insect, it drew its breath through vent-holes, it would not subsist in oil, as by it they would be stopped up.

It is only the first species that is used in medicine, being applied to the skin in or der to draw off blood. With this view they are employed to phlebotomise young children. If the leech does not fasten, a drop of sugared milk is put on the spot it is wished to fix on, or a little blood is drawn by means of a slight puncture, after which it immediately settles. The leech, when fixed, should be watched, lest it should find its way into the anus when used for the hemorrhoids, or penetrate into the œsophagus, if employed to draw the gums, as it would make great havoc in the stomach or intestines. In such a case, the best and quickest remedy is to swallow some salt; which is the method practised to make it loose its hold when it sucks longer than was intended.

H. sanguisuga, horse leech: elongated, olive-brown, with an ochre yellow marginal band: found in stagnant waters, ditches, and ponds from four to six inches long: body above dull olive-black, with an ochre margin on each side; beneath paler, with sometimes a few black spots: tail thicker than the head. This species sucks blood with great avidity, and in large quantities. H. viridis: body depressed, oblong, green, with a transparent margin and pointed tail. This species has been described by Dr. Shaw in the "Transactions of the Linnaan Society:" it inhabits clear cold waters, is about the eighth of an inch long, and like most of the genus has a power of reproduction almost equal to that of the polype; for if the animal be divided in every direction, the parts will become perfect animals, and

may be again divided and again reproduced. It is of a grass-green colour, with a transparent border all round. H. geometra, or geometrical leech: body filiform, greenish, spotted with white; both ends dilatable, and equally tenacious. It inhabits fresh waters: moves as if measuring like a compass, whence the name: it is found on trout and other fish, after the spawning season.

HIRUNDO, the swallow, in natural history, a genus of birds of the order Passeres. Generic character: bill short, depressed at the base, small at the point, and a little bending; nostrils open; tongue short, broad, and cleft; wings long; legs short; tail, in general, forked. These live almost perpetually in the air, and perform in it every act of their nature. They subsist upon the insects with which that element abounds, and which they catch on the wing with the most admirable dexterity; and for this purpose they are furnished with a most extraordinary power of distending their jaws. The service they perform to man by their incessant assiduity in this work of destruction is not lightly to be appreciated, and those who observe the crowded population of the atmosphere through the beams of a summer evening, will easily be led to believe, that, but for the interception of incalculable myriads of insects by these birds, the annoyance of man by these minute animals would be highly distressing, and perhaps almost intolerable. The celerity of this tribe of birds is truly astonishing, and that union of flexibility and speed which they exhibit in pursuit of their prey, or with which they elude the grasp of their enemies, is highly remarkable and interesting. Their manners are eminently entertaining and social. They fix their nests to the habitations of man, and are not only extremely useful in some respects, but perfectly inoffensive in all. Though so much within the observation of man, some circumstances of their economy have hitherto completely baffled the curiosity of the most vigilant observer. Various opinions have been formed of the state in which they exist during the time of their disappearance; some imagining them to lie torpid, in the banks of rivers, or in decayed trees, or in ruined editices or vaults; and others, that they retire for the winter from the air to immense clusters, like the bottoms of rivers. on record, by respectable testimony, in favour of both these hypotheses. It is also attested, on similar authority, that migra

the water, lying in swarms of bees, at Particular facts are

tions of these birds actually take place. They have frequently been seen by mariners at a vast distance from land, and in very numerous flocks, and have occasionally converted the rigging and yards of vessels into resting places, which have most conveniently relieved their long and wearisome flight. Mr. Pearson of London, after one unsuc cessful experiment, was enabled to preserve swallows throughout the winter, taking extreme care to guard their feet from damp and cold. They were in good health, sang with vivacity, and accomplished the process of moulting soon after Christmas, with out any particular inconvenience, and for three successive years exhibited the same vigour, health, and animation. From this experiment it might be presumed, that swallows experience no particular deviation in constitution and propensities from other birds, and quit this country towards winter for one where they may enjoy a milder climate, and more plentiful food. They are to be met with in every country of the world, and in all, or nearly so, are found to be migratory. There are thirty-seven species, of which we shall notice the following. H. rustica, or the house-swallow, appears in March in this country, and leaves it in September. It generally builds in chimneys, or under the eaves of houses, and will return, unless interrupted, to its original haunt for a number of years. For three years in succession a pair of swallows built on the frame of an old picture in Camerton Hall, near Bath, having access to the apartment through a broken pane in the window. These birds breed twice a year. They are easily rendered familiar; and it has been calculated, from what occurred in a curious and extraordinary instance of the domestication of one of them, in the family of a gentleman in Northumberland, that a single swallow will devour from seven hundred to a thousand flies in one day. See Aves, Plate VIII. fig. 2.

H. urbica, or the martin, arrives in this country rather later than the swallow, and remains longer. It builds often in the crags of rocks, near the sea; often under the eaves and cornices of houses. As soon as the young are able to fly, they are fed by the old birds upon the wing, by a process so rapid and instantaneous, as almost to be deemed incredible by those who have not actually witnessed it. Before their departure, they collect in immense flocks in the small islands of the Thames, where they roost, and in their flights about which they

almost obscure by their numbers the face of the sky. It is observed, that in comparison with the multitudes which depart, there are extremely few which return. See Aves, Plate VIII. fig. 3.

H. apus, or the swift, arrives later and quits sooner than any other species, and is also larger and stronger. It builds in elevated situations, particularly about churches and steeples. As these birds catch at almost every thing in the air, they are taken sometimes by a cockchaffer, or other insects, tied to a thread. In the Isle of Zante this torturing amusement is practised on them by boys, who catch them indeed often in immense numbers by a string and feathered hook only, which they suspend from some elevated situation. They retire during the heat of the day; but in the morning and evening are incessantly on the wing, taking higher and bolder flights than the swallows, and always keeping separate from them. They leave this island in August. See Aves, Plate VIII. fig. 4.

H. esculenta, or the Chinese swallow, is said to be less than the wren by some authors, while others attribute to it the size of the martin. This bird is principally remarkable for its nest, which, singular as it may appear, is not only used for food, but regarded as one of the greatest luxuries on which the genuine epicure can possibly banquet. The weight of this nest is about half an ounce it is formed in the shape of a half of a lemon, and composed of many easily discriminated layers of a substance somewhat resembling isinglass. The materials which constitute it have been the subject of considerable diversity of opinion, and are not yet (at least in this country) ascertained. It is chiefly applied in soups and ragouts, made of chickens, and mixed with a considerable quantity of ginseng.

HISPA, in natural history, a genus of insects of the order Coleoptera. Antennæ cylindrical, approximate at the base, and seated between the eyes; feelers fusiform ; thorax and shells often spinous or toothed at the tip. There have been twenty-six species enumerated and described, very few of which are to be found in this country. They are separated into three divisions: A. lip-horny, entire. B. lip-membranaceous, subemarginate. C. lip-membranaceous, entire. H. atra is the chief species known in this country, found at the roots of long grass. It is of a deep unpolished black, and has the upper part of the body entirely covered with long and strong

spines, which render it similar to the bristly shell of a chesnut, or to a hedge-hog in miniature. The larva of the hispa is unknown.

HISTER, a genus of insects of the order Coleoptera. Antennæ clavate, the club solid; the last joint compressed, decurved; head retractile within the body; mouth forcipated; shells shorter than the body, truncate; fore-shanks toothed, hind-shanks spinous. There are twenty-four species. The most common European species of the hister genus' is H. unicolor, which is of a. glossy coal black colour, and of a slightly flattened shape. It is often seen in the gardens, bnt its larva is unknown.

HISTORIOGRAPHER, a professed historian, or writer of history. An historian, of all authors, spreads the most ample theatre; he erects the greatest tribunal on earth; for it is his office to sit supreme judge of all that passes in the world, to pronounce the destiny of the great ones of the earth, and fix their character with posterity; to do justice to virtue and worth, in bestowing eternity upon great and good actions, and fixing an everlasting mark of infamy on bad ones; to instruct all people and nations, and direct the conduct of ages; he therefore ought to be endowed with many great and uncommon qualifications. He must be a person of consummate know ledge of men and things, of sound judg. ment, uncommon sagacity and penetration, experienced in matters of state and war, of great integrity, firmness of mind, freedom of sentiment, and master of a pure, clear, nervous, and exalted style. An historian whose province it is to speak to kings and princes, to the great men of all ages and countries, and to be the common master and instructor of mankind, must not only write with purity, simplicity, and manly sense, but with dignity and elegance: he must reject all that is vulgar and low in style, make the majesty and sublimity of his expression comport with the dignity of his subject; must by an exact choice and propriety of words, a natural disposition of phrases, and a prudent moderate use of figures, give weight to his thoughts, force to his language, and imprint a character of greatness on all that he says. He must at the same time represent things with an air of gravity and prudence, and not give a loose to the heat of imagination, or vivacity of wit; but discreetly suppress every thing that shall seem idle, languid and unprofit able, and give every thing that just figure

and proportion which is consistent with propriety and decorum. He must endeavour at a noble simplicity of thought, language, design, and ordinance, and carefully avoid all profuseness of false conceit, strained expression, and affected pompousness so inconsistent with the gravity, dignity, and noble character of history. In a word, he must write so as to be intelligible to the ignorant, and yet charm the wise; form and express such ideas as are great, and yet shall appear very common, and intermix no other ornament with his narration than what the modesty of truth can bear. He should be above the reach and power of hopes and fears, and all kinds of interest, that he may always dare to speak the truth, and write of all without prejudice; religiously observing never to abuse the public faith, nor to advance any thing upon common fame, which is always uncertain, but upon undoubted memoirs and faithful relations of such persons as have had a hand in affairs. He must always be upon his guard against the bias and affections of those who supply him with matter, and must not credulously give his assent to the historians that went before him, without enquiring narrowly into their character, and what influence they may have been under when they wrote, in order to make a just estimate of their weight and credit.

An historian, as to his matter, should choose subjects great in themselves, and such as are worthy of public fame and remembrance; and should make himself so far master of his matter, as to be able to cast it into what form he pleases, and to strike upon all his subjects the colours they are naturally disposed to bear, in order to make his lessons profitable to posterity, by regulating the heart and spirits of men, animating them to great and virtuous actions by illustrious examples, and cautioning them against vice, folly, cruelty, and injustice, by laying open the fatal consequences resulting from them. The course of his narration must proceed in the order of time in which the facts happened, in a pure, grave, uninterrupted series, such as may not improperly be compared to a great river flowing with composed majesty and stately smoothness; and when it falls in his way to introduce little occurrences, they must be so artfully interwoven with the great, in the thread of the narration, as to offer a seasonable entertainment and relief to the reader from the fatigue that too sedulous an attention to the great requireth.

He must also observe great judgment in the ordinance and disposition of events and their circumstances, so as to interest the reader, and let him into all his thoughts and views, by making his persons act as their character and temper inclined them; discovering their manners, sentiments, designs, motives, and operations, as they really stand in a necessary dependence upon cach other, and with so natural a connection, as to show nothing out of its place. His transitions, in which consists the great art of narration, and one of its principal beauties, must be natural and easy, arising from the difference of subject rather than expression. He must make a wise and judicious choice of circumstances, such as are proper to enlarge and improve the ideas of things, and to strike that light and colour upon them which most easily attracts belief and engages the mind; and must for that purpose always observe a due mixture of great and little circumstances, neither of which must be carried beyond nature, or be so minute, low, or frivolous, as to debase his subject. He must not only recite the bare events and actions of men, but also lay open the motives and principles from which they took their rise, and upon which they proceeded to their final issues. He must lay open the hearts of the actors, let his reader into the most important secrets of their councils and designs, and oblige him with a sight of those secret springs which moved them to enterprizes, and of the causes of their success or miscarriage. He must be very sparing and cautious in the use of descriptions, which are to be introduced so far only as they serve to illustrate things that are essential to the main subject, and to enliven the narration: and even in that case they must be succinct and elegant. The frequent use of harangues are disapproved of by many judicious persons; for these long formal harangues of generals to their soldiers, when in the presence of the enemy, and ready to enter upon action, which we find in many historians, are undoubtedly not only unnatural and improbable, but contrary to the truth of history. Nevertheless, a short speech suited to the subject, made by a person of eminent character, has it proper beauty, and animates a narration. A judicious historian ought not to admit any portraits into his work but those of the greatest persons, and such as are principally interested, and have the chief haud in affairs; and these must be real, natural, and truly resembling their

originals; expressive of their genius, the qualities of the head and heart, rather than descriptive of the external form of his personages. When such are finished with a masterly hand, with true judgment and success, they are not only great ornaments and embellishments in history, but of use to strip the hearts of men of their disguises, to lay open all their secret folds, and disclose the real springs of actions. It is a great fault in an historiographer to abound too' much in reflections of his own; he therefore must not turn philosopher or moralist indif ferently upon all occasions; for every man desires to be free in his judgment of the facts represented to him, and the consequences he is to draw from them, in which consists the greatest pleasure of the reader. But if an author should throw in, or mingle reflections of his own with his story, they must be such as arise naturally from the subject, and contain a great and noble sense in a few words; they must not be too fine spun or studied, nor have more brightness than solidity, but appear rather to be the reasoning of a wise statesman than the affec tation of a declaimer; nor must they be too frequent, or too loose and disjointed, but be enamelled in the body of the work. Digressions, if made with judgment, and not too wide and foreign from the subject, have also their proper grace and ornament in history; as they give an agreeable variety to the narration, and relieve the mind of the reader; but they must be introduced by the historian with an artful hand and great address; they must bear an alliance and connection with the purport of the history, and their length must be proportionably greater or less, as they are more nearly or remotely allied to the capital point of the story.

HISTORY is a connected recital of past or present events.

If the value of each department of knowledge is to be ascertained by the esteem in which it is held by the generality of. readers, a place of distinguished honour must be assigned to history. Gratifying that curiosity, which is innate in the mind of man, it is equally delightful to those whose intellect is just dawning, and to those whose faculties are matured by the lapse of time and the process of cultivation. Comparatively few have a relish for abstract speculations; but almost all are delighted by the display of facts. By the pictures, which are exhibited in a faithful narration the fancy is gently excited, and