Page images
PDF
EPUB

predecessors. This prospect gives us a kind of security for the continual propagation and extension of knowledge; and that, for the future, no more great chasms of men really eminent for knowledge will ever disfigure that part of the chart of their lives which I cannot draw, or ever see drawn. What a figure must science make, advancing as it now does, at the end of as many centuries as have elapsed since the Augustan age!"

BIPED, in zoology, an animal furnished with only two legs. Men and birds are bipeds. Apes occasionally walk on their hind legs, and seem to be of this tribe; but that is not a natural position for them, and they rest upon all their legs, like other quadrupeds. The jerboas are also of the latter description, jumping and leaping on their hind legs, but resting on the fore legs likewise.

BIQUADRATIC power, in algebra, the fourth power or squared square of a number, as 16 is the biquadratic power of 2; for 2 X 2 is 4, and 4 × 4 is equal to 16.

BIQUADRATIC root of a number, is the square root of its square root: thus the biquadratic root of 81 is 3; for the square root of 81 is 9, and the square root of 9 is 3.

BIQUADRATIC equation, an equation where the unknown quantity of one of the terms has four dimensions.

Any biquadratic equation may be conceived as generated by the multiplication of four simple equations. Thus, if x=a, x=b, x=c, x=d, or x—a = 0, x —

b=0, x- —c=0, x—d=0; then will x-a x x --b x x -c x x -- d= 0, beget a biquadratic equation. Or it may be formed of two quadratic equations, as x2 + bx + c × x2+ dx+e=0); or, lastly, it may be produced from the multiplication of one cubic and one simple equation, as xa x x + c x2 + d x + c = 0. For an account of the resolution of biqua dratic equations see EQUATIONS.

BIQUINTILE, an aspect of the planets, when they are 144 degrees from each other. BIRCH tree. See BETULA. BIRD, in zoology- See AVES. BIRD-catching, the art of taking birds or wild fowl, whether for food, for the pleasure of their song, or for their destruction, as pernicious to the husbandman, &c. The methods are by bird-lime, nets, decoys,&c. In the suburbs of London are several weavers and other tradesmen, who, during the months of October and March, get their

livelihood by an ingenious, and, we may say, a scientific method of bird-catching, which is totally unknown in other parts of Great Britain. The reason of this trade being confined to so small a compass arises from there being no considerable sale of singing birds, except in the metropolis: as the apparatus for this purpose is also heavy, and at the same time must be carried on a man's back, it prevents the bird-catchers going to more than three or four miles distance.

This method of bird-catching must have been long practised, as it is brought to a most systematical perfection, and is attended with a very considerable expense. The nets are a most ingenious piece of mechanism; they are generally twelve yards and a half long, and two yards and a half wide; and no one, on bare inspection, would imagine, that a bird, who is só very quick in all its motions, could be catched by the nets flapping over each other, till he becomes an eye-witness of the pullers seldom failing. The wild birds fly, as the bird-catchers term it, chiefly during the month of October, and part of September and November, as the flight in March is much less considerable than that of Michaelmas. It is to be noted also, that the several species of birds of flight do not make their appearance precisely at the same time, during the months of September, October, and November. The pippet, a small species of lark, for example, begins to fly about Michaelmas ; and then the woodlark, linnet, goldfinch, chaffinch, greenfinch, and other birds of flights succeed, all of which are not easily to be caught, or in any numbers at any other time, and more particularly the pippet and the woodlark. These birds, during the Michaelmas and March flights, are chiefly on the wing from day-break to noon, though there is afterwards a small flight from two till night; but this however is so inconsiderable, that the birdcatchers always take up their nets at noon. The bird-catcher generally carries with him five or six linnets, of which more are caught than any singing bird, two goldfinches, two greenfinches, one woodlark, ore redpoll, yellowhammer, titlark, and aberdevine, and perhaps a bullfinch; these are placed at small distances from the nets, in little cages. He has besides what are called flurbirds, which are placed within the nets, are raised upon the flur, or moveable perch, and gently let down at the time the wild bird approaches them. These generally

consist of the linnet, the goldfinch, and the greenfinch, which are secured to the flur by what is called a brace or bandage, a contrivance which secures the birds without doing any injury to their plumage. When the bird-catcher hath laid his nets, he disposes of his call-birds at proper intervals. It must be owned that there is most malicious joy in these call-birds, to bring the wild ones into the same state of captivity; which may likewise be observed with regard to the decoy ducks. See DECOY.

Their sight and hearing infinitely excel that of the bird-catcher. The instant that the wild birds are perceived, notice is given by one to the rest of the call-birds, (as it is by the first hound that hits on the scent to the rest of the pack) after which follows the same sort of tumultuous ecstasy and joy. The callbirds, while the bird is at a distance, do not sing as a bird does in a chamber; they invite the wild ones by what the bird-catchers call short jerks, which, when the birds are good, may be heard at a great distance. The ascendency by this call or invitation is so great, that the wild bird is stopped in its course of flight; and, if not already, acquainted with the nets, lights boldly within 20 yards of perhaps three or four birdcatchers, on a spot which otherwise it would not have taken the least notice of Nay, it frequently happens, that if half a flock only are caught, the remaining half will immediately afterwards light in the nets, and share the same fate; and should only one bird escape, that bird will suffer itself to be pulled at till it is caught; such a fascinating power have the call-birds.

The nightingale is not a bird of flight, in the sense the bird-catchers use this term. Like the robin, wren, and many other singing birds, it only moves from hedge to hedge, and does not take the periodical flights in October and March.

The persons who catch these birds, make use of small trap-nets, without call-birds; and are considered as inferior in dignity to other bird-catchers, who will not rank with them. The arrival of the nightingale is expected by the trappers in the neighbourhood of London, the first week in April: at the beginning, none but cocks are taken; but in a few days the hens make their appearance, generally by themselves, though sometimes a few males come along with them. The latter are distinguished from the females not only by their superior size, but by a great swelling of their vent, which commences on the first arrival of the hens.

They are caught in a net-trap, the bottom of which is surrounded with an iron ring; the net itself is rather larger than a cabbage-net. When the trappers hear or see them, they strew some fresh mould under the place, and bait the trap with a mealworm from the baker's shop. Ten or a dozen nightingales have been thus caught in a day.

The common way of taking larks, of which so many are used at our tables, is in the night, with those nets which are called trammels. These are usually made of 36 yards in length, and about six yards over, with six ribs of packthread, which at the ends are put upon two poles of about 16 feet long, and made lesser at each end. These are to be drawn over the ground by two men, and every five or six steps the net is made to touch the ground, otherwise it will pass over the birds without touching them, and they will escape. When they are felt to fly up against the net, it is clapped down, and then all are safe that are under it. The darkest nights are properest for this sport; and the net will not only take larks, but all other birds that roost on the ground, among which are woodcocks, snipes, partridges, quails, fieldfares, and several others.

In the depth of winter, people sometimes take great numbers of larks by nooses of horse hair. The method is this: take 100 or 200 yards of packthread; fasten at every six inches a noose made of double horse hair; at every 20 yards the line is to be pegged down to the ground, and so left ready to take them. The time to use this is when the ground is covered with snow, and the larks are to be allured to it by some white oats scattered all the way among the nooses. They must be taken away as soon as three or four are hung, otherwise the rest will be frighted; but though the others are scared away just where the sportsman comes, they will be feeding at the other end of the line, and the sport may be thus continued for a long time.

Those caught in the day are taken in clap-nets of 15 yards length, and two and a half in breadth, and are enticed within the reach by means of bits of looking-glass, fixed in a piece of wood, and placed in the middle of the nets, which are put in a quick whirling motion by a string the larker commands; he also makes use of a decoy lark. These nets are used only till the 14th of November; for the larks will not dare, or frolic in the air, except in fine sunny wea

ther; and, of course, cannot be inveigled into the snare. When the weather grows gloomy, the larker changes his engine, and makes use of a trammel-net, twenty-seven or twenty-eight feet long, and five broad; which is put on two poles, eighteen feet long, and carried by men under each arm, who pass over the fields, and quarter the ground as a setting dog: when they hear or feel a lark hit the net, they drop it down, and so the birds are taken.

. But the most singular species of birdcatching is on the Holm of Ness a vast rock severed from the isle of Ness by some unknown convulsion, and only about sixteen fathoms distant. It is of the same stupendous height as the opposite precipice, with a raging sea between; so that the intervening chasm is of matchless horror, Some adventurous climber reaches the rock in a boat, gains the height, and fastens several stakes on the small portion of earth which is to be found on the top; correspondent stakes are placed on the edge of the correspondent cliffs: a rope is fixed to the stakes on both sides, along which a machine, called a cradle, is contrived to slide; and, by the help of a small parallel cord, fastened in like manner, the adventurer wafts himself over, and returns with his booty.

The manner of bird-catching, in the Feroe islands, is very strange and hazardous. Necessity compels mankind to wonderful attempts. The cliffs which contain the objects of their search are often two hundred fathoms in height, and are attempted from above and below. In the first case, the fowlers provide themselves with a rope eighty or one hundred fathoms in length. The fowler fastens one end about his waist and between his legs, recommends himself to the protection of the Almighty, and is lowered down by six others, who place a piece of timber on the margin of the rock, to preserve the rope from wearing against the sharp edge. They have besides a small line fastened to the body of the adventurer, by which he gives signals that they may lower or raise him, or shift him from place to place. The last operation is attended with great danger, by the loosening of the stones, which often fall on his head, and would infallibly destroy him, was he not protected by a strong thick cap; but even that is found unequal to save him against the weight of the larger fragments of rock. The dexterity of the fowlers is amazing; they will place their feet against the front of the

precipice, and dart themselves some fathoms from it, with a cool eye survey the places where the birds nestle, and again shoot into their haunts. In some places the birds lodge in deep recesses: the fowler will alight there, disengage himself from the rope, fix it to a stone, and at his leisure collect the booty, fasten it to his girdle, and resume his pendulous seat. At times he will again spring from the rock, and in that attitude, with a fowling net placed at the end of a staff, catch the old birds which are flying to and from their retreats. When he has finished his dreadful employment he gives a signal to his friends above, who pull him up, and share the hard-earned profit. The feathers are preserved for exportation; the flesh is partly eaten fresh; but the greater portion dried for winter's provision.

The fowling from below has its share of danger. The party goes on the expedition in a boat; and when it has attained the base of the precipice, one of the most daring, having fastened a rope about his waist, and furnished himself with a long pole with an iron hook at one end, either climbs or is thrust up by his companions, who place a pole under his breech, to the next footing spot he can reach. He, by means of the rope, brings up one of the boat's crew; the rest are drawn up in the same manner, and each is furnished with his rope and fowlingstaff. They continue their progress upwards, in the same manner, till they arrive at the region of birds; and wander about the face of the cliff in search of them. They then act in pairs; one fastens himself to the end of his associate's rope, and in places where birds have nestled beneath his footing, he permits himself to be lowered down, depending for his security on the strength of his companion, who has to haul him up again; but it sometimes happens, that the person above is overpowered by the weight, and both inevitably perish. They fling the fowl into the boat, which attends their motions, and receives the booty. They often pass seven or eight days in this tremendous employment, and lodge in the crannies which they find in the face of the precipice.

Birds are likewise caught in traps of various kinds; and frequently by nooses of hairs. In this way great numbers of wheatears are annually taken on the various downs of England, particularly in Sussex, Small holes are dug by the shepherds in the ground, in each of which is placed a noose.

Whenever a cloud obscures the sun, these timid birds seek for shelter under a stone, or creep into any holes that present themselves; and they are thus ensnared by the nooses which fasten around their necks. Woodcocks and snipes are taken likewise by nooses of horse hair placed along their paths, in marshes and moist grounds. Wild ducks, in all their varieties, are taken in vast numbers every winter on our coasts, by means of decoys. See DECOY.

Grouse and partridges are taken by means of nets, either at night when resting on the ground, by observing where they alight, and, when settled, drawing a net over that part of the field; or, in the day, a very steady dog is used to point at them. The attention of the birds being thus fixed, two persons, drawing the two extremities of a large net, pass it over them, and thus secure a whole pack of grouse, or covey of partridges at once.

Pheasants are sometimes taken by night, by holding flaming sulphur under the trees on which they are observed to perch, the suffocating effiuvia of which makes them fall senseless.

BIRD lime. The vegetable principle to which is given the name of bird-lime, was first examined by Vauquelin, who found it possessed of properties different from every other. It was found collected on the epidermis of a plant brought to Europe by Michaud, and called robinia viscosa, constituting a viscid substance, which made the fingers adhere to the young twigs. From the late analysis of bird-lime by Bouillon la Grange, it is obvions that it owes its peculiar properties to the presence of an analogous substance, which indeed constitutes the essential part of that composition. Hence the reason of the name of bird-lime to the principle itself. 1. Natural bird-lime (or that which exudes spontaneously from plants) possesses the following properties: its colour is green; it has no sensible taste or smell; is extremely adhesive; softens by the heat of the fingers, and sticks to them with great obstinacy. When heated it melts, swells up, and burns with a considerable flame, leaving a bulky charcoal behind it. It does not dissolve in water; alcohol has but little action on it, especially when cold. By the assistance of heat it dissolves a portion of it; but in cooling, allows the greatest part to precipitate again, When exposed to the air it continues glutinous, never becoming hard and brittle like the resins. It combines readily with oils.

Ether is its true solvent, dissolving it readily without the assistance of heat. The solution is of a deep green colour. The alkalies do not combine with it; the effect of the acids was not tried. These properties are sufficient to distinguish bird-lime from every other vegetable principle. 2. Artificial bird-lime is prepared from different substances in different countries. The berries of the misletoe are said to have been formerly employed. They were pounded, boiled in water, and the hot water poured off. At present bird-lime is usually prepared from the middle bark of the holly. The process followed in England is as follows: the bark is boiled in water seven or eight hours, till it becomes soft. It is then laid in quantities in the earth, covered with stones, and left to ferment or rot for a fortnight or three weeks. By this fermentation, it changes to a mucilaginous consistency. It is then taken from the pits, pounded in mortars to a paste, and well washed with river water. Its colour is greenish, its flavour sour, and its consistence gluey, stringy, and tenacious. Its smell is similar to that of linseed oil. When spread on a glass plate and exposed to the air and light it dries, becomes brown, loses its viscidity, and may be reduced to a powder; but when water is added to it, the glutinous property returns. It reddens vegetable blues. When gently heated it melts and swells, and emits an odour like that of animal oils. When heated on red hot coals, it burns with a lively flame, and gives ont a great deal of smoke, leaving a white ash, composed of carbonate of lime, alumina, iron, sulphate, and muriate of potash. Weak acids soften bird-lime, and partly dissolve it; strong acids act with more violence. Sulphuric acid renders it black; and when lime is added to the solution, acetic acid and ammonia separate. Nitric acid cold has little effect; but when assisted by heat it dissolves the bird-lime; and the solution, when evaporated, leaves behind it a hard brittle mass. By treating this mass with nitric acid, a new solution may be obtained, which by evaporation yields malic and oxalic acids, and a yellow matter which possesses, several of the properties of wax. Cold muriatic acid does not act on birdlime; hot muriatic acid renders it black. Bird-lime, when treated with oxymuriatic acid, becomes white, and is divided into hard compact masses, having unaltered bird-lime in their centre. This white substance may be pulverised; it is insolable in water; does

not melt when heated; and when treated with nitric acid, it neither becomes yellow, nor does it yield resin. Acetic acid softens bird-line, and dissolves a certain portion of it. The liquid acquires a yellow colour. Its taste is insipid. When carbonate of potash is dropped into this solution, no precipitate falls. By evaporation it yields a resinouslike substance. Some of the metallic oxides are reduced when heated with bird-lime. Litharge combines with it, and forms a kind of plaster. Alcohol of the specific gravity 0.817 dissolves bird-lime at a boiling heat.

On cooling, it lets fall a yellow matter similar to wax. The filtered liquid is bitter, nauseous, and acid. Water precipitates a substance similar to resin. Sulphuric ether dissolves bird-lime readily, and in great abundance. The solution is greenish. When mixed with water, an oily substance separates, which has some resemblance to linseed oil. When evaporated, a greasy substance is obtained, having a yellow colour and the softness of wax.

On

BIRDS' nests, in cookery, the nest of a small Indian swallow, very delicately tasted, and frequently mixed among soups. the sea coasts of China, at certain seasons of the year, there are seen vast numbers of these birds; they leave the inland-country at their breeding time, and come to build in the rocks, and fashion their nests out of a matter which they find on the shore, washed thither by the waves. The nature of this substance is scarcely yet ascertained. According to Kempfer, it is molluscæ or sea-worms; according to M. le Poivre, fish-spawn; according to Dalrymple, seaweeds; and according to Linnæus, it is the animal substance frequently found on the beach, which fishermen call blubbers or jellies. The nests are of a hemispheric fi gure, and of the size of a goose's egg, and in substance much resemble the ichthyocolla or isinglass. The Chinese gather these nests, and sell them to all parts of the world; they dissolve in broths, &c. and make a kind of jelly of a very delicious flavour. These nests are found in great abundance in the island of Sumatra, particularly about Croe, near the south end of the island. Four miles up the river of that name is a large cave, where the birds build in vast numbers. The nests are distinguished into white and black; of which the first are by far more scarce and valuable, being found in the proportion of one only to twenty-five. The white sort sells in China at the rate of 1000 to 1500 Spanish dollars the pecul;

the black is usually disposed of at Batavia for about 20 dollars the same weight, where it is chiefly converted into glue, of which it makes a very superior kind. The difference between the two has by some been supposed to be owing to the mixture of the feathers of the birds with the viscous substance of which the nests are formed; and this they deduce from the experiment of steeping the black nests for a short time in hot water, when they are said to become in a great degree white. When the natives prepare to take the nests, they enter the caves with torches, and forming ladders according to the usual mode, of a single bamboo notched, they ascend and pull down the nests, which adhere in numbers together, from the side and top of the rocks. They say that the more frequently and regularly the cave is stripped, the greater proportion of white nests they are sure to find, and that on this experience they often make a practice of beating down and destroying the old nests in larger quantities than they trouble themselves to carry away, in order that they may find white nests the next season in their room. The birds, during the building time, are seen in large flocks on the beach, collecting in their bills the foam which is thrown up by the surf, of which there is little doubt but they construct their nests, after it has undergone perhaps a preparation, from a commixture with their saliva, or other secretion with which nature has provided them for that purpose.

BIRDS, singing, are, the nightingale, blackbird, starling, thrush, linnet, lark, throstle, canary-bird, bulfinch, goldfinch, &c. See some very curious experiments and observations on the singing of birds, Phil. Trans. vol. xiii. part ii. No. 31. Their first sound is called chirp, which is a single sound repeated at short intervals; the next call, which is a repetition of one and the same note; and the third sound is called recording, which a young bird continues to do for ten or eleven months, till he is able to execute every part of his song; and when he is perfect in his lesson, he is said to sing his song round. Their notes are no more innate than language in man; they all sing in the same key. The honourable author, Daines Barrington, has attempted to reduce their comparative merits to a scale; and to explain how they first came to have particular notes.

BIRDS, in heraldry, according to their several kinds, represent either the contemplative or active life. They are the em

« PreviousContinue »