circumstances we shall now proceed to describe, another and distinct form of atmospheric ice is produced, termed HAIL.

Sir John Herschel has stated his views of the philosophy of this subject in the following terms: after relating the observation, during a balloon ascent, of the temperature of 46° Fahr. at the height of 12,000 feet, and that of 22° only, or 24° colder, at the same elevation in the descent, a heavy fall of snow being then and there in progress, he says:-"It is evident that this arose from the condensation of vapour at that level, and that, from the intrusion of some current, a mass of intensely cold air had been introduced, which, finding vapour near saturation, converted it into snow. It is equally evident," he continues, "that had the latter condition prevailed, not at the level in question, but at a somewhat higher, where the condensation might hav been into rain very near the freezing point, the drops in descending would have been frozen solid, and fallen as hail. It might have been so equally, had the precipitation been so copious as to allow the coalescence of a great number of minute particles in a nascent state into drops frozen together instanter, since there is good reason to believe that the solid form is never assumed without transition through the liquid, however momentary.[*] The generation of hail seems always to depend on some such very sudden introduction of an extremely cold current of air into the bosom of a quiescent, nearly saturated mass. Hailstorms are always purely local phenomena, and never last long. They often mark their course by linear tracks of devastation, of great length and very small breadth. In the hailstorm of July 13, 1788, which passed across France from south to north, two such tracks were marked, of 175 and 200 leagues in length respectively, parallel to each other, the one four leagues broad, the other two, and separated by a tract five leagues in breadth in which only rain fell. A similar character is very common, though not to such an extent. Such linear hailstorms are always attended with violent wind, sudden depression of the barometer, indicating a great commotion in the air, and probable mingling of saturated masses of very different temperature. Great hailstorms are often preceded by a loud clattering and clashing sound, indicating the hurtling together of masses of ice in the air. The recent experiments of [Professor Faraday and] Professor Tyndall on the re-uniting of broken ice by 'regelation,' or a sort of welding, fully explain the formation, under such circumstances, of large masses of ice of irregular forms in this aërial conflict." (Meteorology, 'Encyc. Brit.' vol. xiv.)

The following account, extracted from the celebrated 'Climate of London,' by Mr. Luke Howard, F.R.S., of a hailstorm as observed at Plaistow, in the county of Essex, near the metropolis (the scene of his first series of meteorological observations), on the 19th of April, 1809, affords an instructive example of the local phenomena of such storms: -"The day had been sultry, like some preceding ones, and overcast with clouds, which during the afternoon gave evident demonstrations of an approaching discharge of electricity. Large and deep cumulostrati were ranged side by side, mingled with the cirro-cumulus and cirro-stratus, the whole having that peculiar, almost indescribable character, which these charged conductors assume when wrought up to the highest state of electric tension. About five in the afternoon, being at the laboratory, and perceiving a continued roll of thunder, with vivid lightning approaching from the south, and the appearance of a heavy shower in that quarter, I anticipated a storm of no common violence. We were proceeding to take measures for the safety of some glass utensils, when in an instant there opened upon us a volley of hail of such tremendous force, as in ten, or at most fifteen minutes, demolished most part of the skylights and south windows in the neighbourhood. These icy bullets, some of them a full inch in diameter, were discharged almost horizontally from a cloud to the windward, and in such quantity as to be drifted in large masses under the walls. Whether borne by the impetuous blast that came with them, or carrying the air thus before them, I could not determine, but such was the velocity of their motion that in many instances a clear round hole was left in the glass they pierced; and one large pane (which I saw) had two such perforations distinctly formed, the glass otherwise whole. The water in the river, lashed by the hail and raised by the wind, resembled a cauldron boiling violently, rather than waves with breakers. The electrical discharges were incessant, approaching with the cloud and passing off with it: . This sudden irruption over, it rained for a while moderately. The wind was at first E., then S. during the hail, then W., then E., then W. again. About seven, the clouds all at once put off their stormy character. The remainder of the evening was calm and pleasant. A person who was on the road from London to Bow (probably not two miles off) during the storm, informed me that he experienced nothing but continued thunder and lightning, and very heavy rain, the latter appearing luminous on the ground on each side of him, which it often does in heavy storms. It was evident from other circumstances that the hail was bounded in a western direction by the village of Bow, and it reached eastward from thence only about three miles. Its course appears to have been from S. to N., over Blackheath, Bromley, Plaistow, West Ham, and so up the country between the rivers Lea and Roding." The amount of [* On this subject see a paper by Mr. Brayley, On the probable existence of but two States of Aggregation in Ponderable Matter,' Annals of Philosophy, New Serics (for September, 1826,) vol. xii. pp. 195–200.]

damage occasioned by the hail in this case is mentioned in the sequel of this article.

Many other accounts of hailstorms, and remarkable falls of hail, and of hailstones of remarkable character, at various periods, in England and other countries, are distributed through the Climate of London.'

In the article Hail,' in Brande's 'Dictionary of Literature, Science, and Art,' it is stated that "Hail usually precedes storms of rain, sometimes accompanies, but never or very rarely follows them, especially if the rain is of any duration. The time of its continuance is always very short, generally only a few minutes, and very seldom so long as a quarter of an hour." The writer of the article referred to further remarks, that "the clouds from which hail is precipitated appear to be of very considerable extent and depth, inasmuch as they produce a great obscurity. It has been remarked," he adds, "that they have a peculiar gray or reddish colour, and that their lower surfaces present enormous protuberances, while their edges exhibit deep and numerous indentations." Other characters of these clouds have just been noticed.

Single hailstones have generally a crystalline structure, radiating from a centre if large, forming spherical, oval, or rounded masses, often marked out (on making a section,) into concentric layers, like the rings in the section of the trunk or branch of a tree. The form is often conical, with a rounded base, when they appear to consist of fibres meeting at the apex, but there is reason to believe that these are portions of spheroidal concentric-laminar concretions. They fall from the size of small peas, or much less, to that of an egg, an orange, or a man's head, and weighing from a few grains up to fourteen pounds and upwards. Very frequently hail falls of which each separate stone is, or originally was, a regular tetrahedral crystal of ice, generally with convex faces, apparently owing to the tendency of crystals belonging to the monometric system of crystallisation to which ice in part belongs, to assume curved forms. Often, these have an obvious concentric-laminar structure, and they are often degraded into a conical form by their solid angles and edges becoming rounded by partial melting during their fall. Some large hailstones of concentric structure have a tetrahedral nucleus, the polyhedral having been gradually converted during accretion into a spheroidal solid. As indicated above, the concentric-laminar is also a fibrous structure in hail as in hæmatite and other terrestrial minerals. In the British Mineralogy' of the late eminent naturalist-draughtsman James Sowerby, a work through which are scattered many valuable facts, is an excellent plate of a mass of tetrahedral hailstones, with separate figures of the constituent crystals and their structure. Sir J. Herschel has cited from Dr. Thomson's 'Introduction to Meteorology' a remarkable example of large hailstones of a radiated structure, but such as to evince that the particular stone examined had been formed in passing through two distinct regions of condensation in the air. He also cites from Dr. Buist the observation that in India the hailstones are from five to twenty times larger than the average magnitude of those in England, often weighing from six ounces to a pound, being seldom less than walnuts in size, often as large as oranges and pumpkins. The storms in which they are produced are almost always accompanied by violent wind and rain, thunder and lightning, and are frequent in the delta of the Ganges, especially in the low country within fifty miles of the Bay of Bengal.

Sir J. Herschel, also, after alluding, as above, to the effect of regelation in producing masses of ice in the air by the consolidation of aggregated hailstones, remarks, that "such are recorded to have fallen of almost fabulous magnitude," of which, but with great caution, he proceeds to recite several examples. The effect of the process of regelation (or to adopt the recent correction of Professor James Thomson, of that of melting and regelation) in converting congeries of hailstones into masses of ice is indubitable, but we are in need of sufficiently authenticated statements of the actual fall of such masses. We appear not to have any account of such a phenomenon by a qualified observer, and it is to be believed that in many instances a mass of ice really produced on the ground by the consolidation of hailstones which have fallen within a small area and heaped one upon another, has been supposed to have actually fallen ready formed. The following case from Dr. J. D. Hooker's' Himalayan Journals' will illustrate the view now taken. On the 20th of March, 1849, at noon, a violent hailstorm coming from the south-west, occurred in the Terai, or damp forest-tree region, intervening between the plains of India and the Himalaya mountains, in this locality the Sikkim Himalaya. The hail was of "a strange form, the stones being sections [sectors or segments] of hollow spheres, half an inch across and upwards, formed of cones with truncated apices and convex bases," aggregated with their bases outwards. The fall of the large masses was followed by a shower of the separate conical pieces, and that by heavy rain. "On the mountains this storm was most severe : the stones lay at Dorjiling [of which place the mean temperature in March is 45° Fahr.] for seven days, congealed into masses of ice several feet long and a foot thick, in sheltered places. At Purneah, fifty miles south, stones one and two inches across fell, probably as whole spheres." Mr. Howard quotes a notice of a hailstone fallen in Hungary in 1803, which is stated to have exceeded the strength of eight men to lift it. This, he remarks, recognising (as far back as 1833) the fact as well as the principle of what is now

termed regelation, was doubtless "what is called an ice-board' formed by hail agglutinated in a hollow, by partial fusion on the surface, the whole freezing again by the intense cold within." The largest hailstones are stated to be of very rugged and irregular form, resembling portions of a great sheet of ice broken into pieces. An American observer, the Rev. D. A. Clark, cited in the Climate of London,' saw in the heat of summer, hailstones about one-fourth or three-eighths of an inch thick, and of sufficient diameter to hide a shilling, almost every one of which was perforated in the middle, as if it had been held between the fingers till thus melted. When the perforation was not complete, there was in every case a tendency to it. These were probably of the concentric spheroidal laminar structure, in which the central portions were incomplete. Mr. Howard has himself described a freezing shower which fell at Plaistow on the 19th of January, 1808, and which glazed the windows, and encrusted the walls, and encased the trees, the garments of passengers, and the plumage of birds. A portion being received on a sheet of paper was found to consist of hollow spherules of ice, filled with water; of transparent globules of hail, and of drops of water at the point of freezing, which became solid on touching the bodies they fell upon. As it is stated that the thermometer exposed from the windows indicated 30.5°, the temperature of these drops must have been below the freezing point, their solidification taking place, agreeably to the property of water in that condition, on the agitation of their particles occasioned by their impact on the surface upon which they fell. Had the process of freezing proceeded further before the fall of the shower the hollow spherules filled with water would have become ordinary hailstones with a cavity in the centre.

The electrical character of showers of hail has already been alluded to, and is well exemplified by the following account, given by Mr. Howard, of one which fell, with many others, in different parts of England, on the 19th of April, 1807, at Plaistow. Being carefully examined throughout, it presented the following phenomena: When the cloud discharging it-of course a nimbus [CLOUD]--" was on the horizon, N.E., and the shower behind it, the pith-balls of the insulated electrical conductor [of Mr. Howard's fixed apparatus for investigating the electricity of the atmosphere] remained in contact. When the extremity of the upper surface of the inverted cone of cloud had arrived in the zenith, they opened negative, and diverged slowly to full two inches, at which time pretty strong sparks were drawn from the conductor. During the remainder of the approach of the shower, they gradually closed again. At the moment when the latter [the shower] began to touch the observatory, they opened positive, diverged more speedily, and the apparatus gave strong sparks for a considerable time positive. As the cloud drew off to the S.W. this change gradually ceased, and the balls opened again negative, diverging gradually as before, then converging, and lastly were left a little charged positive." In all this, as Mr. Howard points out, we see the natural effects of the high positive charge in the column of falling hail, which may probably have been six or seven miles in diameter, and which appeared to be surrounded with a negative area, extending into the dry atmosphere about three miles in every direction. This very considerable quantity of electricity, and that of some intensity, was conveyed by an amount of hail comparatively insignificant; for when melted into the rain-gauge, together with that of several previous showers, it did not produce more than a hundredth of an inch of water in depth. It is an example of the fact we shall have to consider elsewhere, of how powerful an electrical charge ice is capable of receiving.

Saussure, as cited by Mr. Howard, attributed the greater or less prevalence of hailstorms in particular localities of the Alps to the relation of their electricity to that of the neighbouring mountains, the clouds or storms being either attracted or repelled by them, according as the electricity is similar or opposed to that of the mountains. Borgo Franco, in Piedmont, he had been informed, was peculiarly subject to the calamity of hailstorms; and it has often been observed, he states, that in other plains bordering on high mountains, at a certain distance from the mountains, hail is much more frequent than in places that lie somewhat nearer or more remote. There are distances, too, Saussure adds, that seem privileged, where hail very seldom falls. On an estate on the river Arve, not quite half-a-league from the foot of Mount Salêve, there had not been within the memory of man any considerable fall of hail, the stormy clouds passing always nearer to the mountain or at a greater distance from them.

Arago (Meteorological Essays,' transl. into English, pp. 106-108) mentions some instances in which the aqueous precipitations from the atmosphere during thunderstorms, whether liquid or solid, have been observed to be luminous, one of which is the luminous rain during a hailstorm already cited from the 'Climate of London.' Among them is one recorded by Lampadius, who was informed by some miners at Freyberg that the small hail which fell during a thunderstorm on the 25th of January, 1822, was luminous when it reached the ground. These cases are doubtless to be explained by the high electrical charge which everything acquires during some thunderstorms; there are experiments with electrical apparatus in which corresponding luminous phenomena are occasioned.

The practice appears to have originated in the last century of making fires on the ground, and of discharging artillery and otherwise exploding gunpowder, on the approach of storms, for the purpose of

dissipating them, and especially of preventing the formation or the fall of hail. Arago (loc. cit. pp. 212-218) has given an account of this practice, of the efficacy of which he considers that there is no sufficient evidence, if even the tendency of the evidence is not to show that continuous discharges of artillery may induce local thunderstorms. On the other hand, the experience of the Marquis de Chevriers, in preserving his lands from the ravages of hailstorms by the explosion of boxes of gunpowder, which he caused to be fired on the neighbouring heights on the approach of a storm, while the villages in the vicinity frequently experienced their baneful effects, does not appear to have been sufficiently considered by that philosopher. There are some grounds for believing, also, that the particular conditions of the atmosphere which result in the formation of hail may be counteracted by fires. Matteucci, the eminent Italian physicist, whose electrical researches continue to enrich science, informed Arago that there is a parish near Cesena, in Romagna, throughout the extent of which, for seven miles round, the peasants, by the curé's advice, place at about every 50 feet heaps of stone and brushwood, which they set on fire when a storm is seen approaching. This practice had been in force for three years, during which time the parish had not suffered either from thunderstorms or from hail, although it formerly suffered much every year from hail, and the neighbouring parishes had continued to do so during the period. "Three years," Arago remarks, however, " are not a sufficiently long period of time to allow of any definitive conclusion as to the preserving influence of large fires. The experiment is being continued, and the public will not fail to be informed of the results."

The principle of insurance has been applied to indemnify persons for the very heavy losses sometimes occasioned by these meteorological phenomena, both by the Royal Farmers' and General Insurance Institution and by a society connected with the Norwich Union Insurance Company. The uncertainty which exists in reference to the occurrence of these frequently calamitous storms in any particular locality, and the circumstance that, while no human sagacity can foresee or prevent them, it is utterly impossible to produce them by fraud, appear to render such casualties peculiarly fit, so soon as observation and experience shall have established accurately the average risk, for the application of a principle which has long been applied to casualties of a nature less uncertain, more easily provided against, and which afford greater opportunities for deceit and imposition. The Hail-storm Insurance societies have published chronological lists of the most remarkable hailstorms in this country during the present century, which present an array of destructive calamities far exceeding what might have been expected from their rarity. It is curious also to observe that they appear to have increased in frequency of late years. In one case, which we select solely from the more circumstantial way in which the details are given, many farms of corn were (on the 14th of July, 1824) literally destroyed in Hertfordshire, Middlesex, and Essex'; the damage done upon a space of 3487 acres in the last-mentioned county alone was estimated at 14,574l., or about 47. 38. 7d. per acre, upon an average. It is stated that this was the third time within a period of thirty years that the crops in the north-western part of that county had been destroyed in like way. During the great hail storms in the months of July and August, 1843, by which immense damage was done in Cambridgeshire, Norfolk, Suffolk, Essex, Hertfordshire, Berkshire, Kent, Oxfordshire, Bedfordshire, Gloucestershire, and Yorkshire, several cases of individual loss amounted to upwards of 20007. The breakage of glass in windows and skylights, and more especially in conservatories and hothouses, is one of the most frequent injuries inflicted by hail-storms, the masses of ice which fall being sometimes sufficient to demolish the wooden framework also. Such extraordinary cases of devastation will be fully accounted for if it be considered that, as it is stated in a paper issued by the Farmers' Insurance Institution, on the authority of Leslie's Elements,' “hailstones having a diameter of two inches," a size which has been exceeded in several well-authenticated cases, "will fall with a velocity of 1134 feet in a second, or more than 1 mile in a minute." In the hail-storm of the 19th of May, 1809, Mr. Howard's account of which has been given above, it is estimated that 200,000 panes of glass were broken in the immediate vicinity of London alone, besides great damage being done in fields and gardens, and the foliage and branches of trees being cut off. An equal number of panes is supposed to have been broken in the northern suburbs of the metropolis on the 30th of July, 1826. In the denser parts of the metropolis itself less damage appears to be done on such occasions, probably because the vast column of heated air always rising from it alters the local atmospheric condition requisite for the production of large hail.

Hailstones of from six to eight or nine inches in circumference are frequently mentioned as having fallen in this country, in the lists referred to, which are compiled from contemporary publications; and on the 3rd of August, 1824, when the eastern part of Suffolk was visited by a violent hail-storm, by which fowls and game, as well as glass and crops, were extensively destroyed, the ice accumulated in some places to a surprising depth. In many cases a considerable extent of ground has been covered to the thickness of several inches. It is worthy of remark how very large a proportion of the destructive storms are recorded to have occurred in the months of June and July. Without noticing the cases in which two or more storms which occurred

The copious lists of hailstorms published by the Farmers' Insurance Institution, which gives references to authorities, and in many cases minute details of the damage done, appeared in the advertising sheet of the Farmer's Almanac' for 1845.

Mr. Howard remarks, in agreement with the results in the table just given, that hail is of rare occurrence in the winter, in England; if we except a sprinkling of small opaque grains which in the fore part of the night indicate the approach of a low temperature, and are found on the frozen ground, and on the ice of the ponds in the morning. Mr. Alfred R. Wallace, in the account of the climate of the valley of the Amazon, appended to his Travels' on that river, cites an authentic account of a fall of hail on the Upper Amazon; a remarkable occurrence, he observes, at a place only three degrees south of the equator, and about two hundred feet (only) above the level of the sea. Children were out at play, and brought the hail to their parents, astonished at a substance falling from the clouds which was quite new to them and so remarkably cold. [ICE; METEOROLOGY; SNOW.]

HAINAULT SCYTHE. [HARVEST.] HAIR-MANUFACTURES. There is a considerable amount of industry bestowed upon human hair and the hair of certain quadrupeds, in the production of manufactured articles. Some of their uses depend upon the felting properties of a few kinds of hair [FELTING; HAT MANUFACTURE]; some upon the great strength of the fibre; and some upon the beautiful gloss of which it is susceptible. Human hair and horse-hair may be taken as the two chief materials for these manufactures. Human Hair.-The hair-trade is a much more important one than would usually be supposed. It was stated in the Quarterly Review' a few years ago (No. 184) that London alone imports more than 100 cwts. of human hair annually, chiefly for making perukes and false curls. The mere clippings would not suffice; there must be a regular harvest of hair. A German has had the patience to count the number of hairs in an average adult female head (probably among his own countrywomen), and finds it to be 110,000,-the blonde being most numerous but finer in substance; the red least numerous but coarser. The light hair imported by or for the hair-workers is brought mostly from Germany, by a Dutch company whose agents periodically visit London; the dark hair more usually comes from France. Some years ago, light golden tresses were much in favour, and the German hair had a good market; but now French hair is more used. Young women in England, who have beautiful tresses, are sometimes urged by poverty to part with them for money to the hair-workers; but in France it is a regular system. There are hair merchants in Paris, who send agents in the spring of each year into the country districts to purchase the tresses of young women, who seek to cultivate an annual crop with the same care as a farmer would a field crop. The agents frequent fairs and markets; and have with them a stock of handkerchiefs, muslins, ribbons, &c., which they give in exchange for the hair. So sensitive a barometer is commerce, of slight changes in the value of exchangeable goods, that the agents know the hair of a particular district to be worth a few sous more per pound than that of a district thirty or forty miles away: a fact which naturalists would have been long in finding out. It is estimated that 200,000 lbs. of hair are purchased at each spring harvest. The price paid is about five francs per lb. on an average; but choice specimens fetch much more. The agents send the hair to their employers, by whom it is dressed and sorted, and sold to the hair-workers in the chief towns at about ten francs per lb. That which is to be made into perukes is purchased by a particular class of persons, by whom it is cleaned, curled, prepared to a certain stage, and sold to the peruke maker at twenty to eighty francs per pound. The peruke maker gives it the form which, as is well known, commands a very high price; a peruke is often sold for double its weight in silver. Both of the hair itself, and of perukes and other articles made of hair, France supplies a considerable quantity to England and the United States.

Besides the making of perukes, false curls, &c., hair-jewellery, so called, is another of the minor manufactures from human hair. Bracelets, armlets, lockets, brooches, earrings, and other articles for personal decoration, are made either wholly of hair, or of hair in combination with other materials. No hair-harvest is necessary for a

supply of materials; the ordinary clippings are sufficient. The hair goes through numerous manipulations on a small scale. It is laid straight to prevent entanglement; cleaned with warm water and soda; dried on a soft towel; gently drawn between brushes; and sorted into different finenesses and lengths. By the aid of small leaden plummets, pieces of strong thread, and a work-table with peculiar marks and holes on its upper surface, the hairs are made to twist or curl or knot round one another, something in the manner of pillowed lace; a pattern marked on paper or pasteboard being placed on the table immediately beneath the work. For making such small articles as lockets and brooches, advantage is taken of the facility with which hair curls up when a heated iron is applied to it; it depends upon a gradual application of this heated iron to produce the required degree of curvature in the curl. The Great Exhibition in Hyde Park contained specimens of hair-work, representing portraits, trophies, temples, &c., as remarkable for patient industry as for defective taste.

Horse-hair, &c.-Various manufactured articles in horse-hair possess qualities which could not be found in any other substance easily obtainable. The horse-hair differs greatly in length and colour. Some of the white hair from the tail of Russian horses is as much as forty inches in length, possessing great evenness, elasticity, and gloss. Various other kinds, black, gray, and white, come to market in lengths from twenty to forty inches. Some kinds are fitted for the stuffing of sofas and other articles of furniture; while others have the requisite straightness and other qualities for the hairs of violin bows. Horsehair cloth is woven of hair taken from the tail, mostly of Russian or South American horses. If the hair be naturally white, it admits of being dyed green, crimson, scarlet, &c. by carefully conducted processes; but black or gray horsehairs only admit of a black dye, and these are the kinds usually employed for horsehair cloth. Coloured hair-cloth, mostly made at Worcester and Sheffield, and at Paris, is extensively used in railway carriages and the saloons of steam-vessels, as well as in ordinary domestic furniture. In most cases the best haircloth only is made of horse-hair, the cheaper kinds being made of cotton, linen, or worsted; and the brilliancy and permanency of the colours depend as much on these fibres as on the hair. In the weaving of haircloth, the weaver uses a sort of hook-shuttle, which he passes between the threads of the warp from right to left; an assistant places a single hair over the end of the hook, and the weaver draws it through the warp. The process is a very tedious one, for each hair usually constitutes only one throw or thread of weft. Specimens of, hair-cloth are made for conversion into carpets. Horsehair is also made into ropes, sacks, and bags; one manufacturer has made it into muffs. For a cheap kind of stuffing, and as a material in mortar, cow-hair is much used as a substitute for horse-hair. We may mention here that horse-hair is imported to the extent of no less than 20,000 cwt. annually, and that half a million yards of horse-hair cloth are annually exported.

A substitute for hair has recently been introduced as a material for ornamental manufactures. Plaits and curls for head-dresses, as lately observed, are usually made of human hair; but the substitute consists of dyed hemp or flax, aloe fibre, plantain fibre, or China grass. The fibre, when dyed to the requisite colours, is combed or heckled until it presents a glossy surface. To make this into curls, a fixed holder is used, into which is inserted a rod slotted at one extremity. On this rod is placed a tube, slotted at one end and having a pin through it at the other. The fibres, in a damp state, are attached to the slot in the tube; and the tube being caused to turn, the threads assume a curled form, and are attached to the ends of the pin. The tube is then removed from the rod, and a heater inserted to fix the curl in the desired form. The curl is subjected to a final glossing and dressing. There are also attempts now being made to convert the tough fibre of a peculiar South American plant into a substitute for horse-hair.

One peculiar application of hair may be briefly noticed-that of the hair of rabbits and hares, carried on by the Russians. They work up the hair into a kind of felt; press or fashion it into bowls, dishes, plates, and other articles; and varnish it thickly. The materials thus made have the appearance of papier machée or varnished leather, and are strong, light, and durable.

HALLEY'S COMET. [COMETS.] HALO. [METEORS.]

HALOGENS. This term, derived from åλs, salt, is employed in chemistry to designate a class of bodies which form haloid salts with the metals. The halogens are chlorine, bromine, iodine, and fluorine, to which may be added the compound halogen cyanogen. HALOID ETHERS. [ETHERS.]

HALOID SALTS. [SALTS.]

HAMATHIONIC ACID. [EUXANTHIC ACID.]
HAMBRO' BLUE. [COLOURING MATTERS.]

HAMMER, POWER, AND STEAM. A reference was made from FORGE to the present article. It will not be necessary to notice the hammer as a mere tool; but its importance as a machine has become such, that a few lines of description are here requisite.

Power-Hammer.-This name we will give to such hammers as can be worked with greater effect than by the mere muscular force of the hammerman, but with the aid of a power other than steam power. Such machines are now used in very great variety. Froming's forgehammer, applicable to heavy castings, and also to the hammering of

wick to Hamburg. Other cities soon followed the example of Brunswick, and joined the league. The cities were divided into four classes, or quarters, the chief cities of which were Lübeck, Cologne, Brunswick, and Danzig; and the contingent in money, or armed force, was fixed for each. Lübeck was at the head of the league, issued the summons for the regular assemblies of the deputies of all the cities, which were held once in three years at Whitsuntide (the first in 1260), and also for the extraordinary assemblies, generally held once in ten years, in which they solemnly renewed their league, admitted new members, and excluded those that had not observed all obligations, compacts, &c. Lübeck also had the common treasury and the archives.

In 1261 they established in London their factory called the Steelyard; but German merchants had been in possession of it, or of an adjoining building known as the German Guildhall, for more than a century. An inquisition, quoted in Markland's History and Survey of London, of the 28 Henry III.' (1243-4), notices "the Gildhall of the merchants of Cullen" (Cologne), as being in Thames-street, near Dowgate. The number of the towns composing the League fluctuated; probably many which were not entirely free were not recognised as such by the sovereign in whose dominions they were placed, although admitted into the union. Among the principal towns, however, were Bergen in Norway, Berlin, Bremen, Brunswick, Colberg, Cologne, Cracow, Danzig, Deventer, Dorpat, Elbing, Frankfort on the Oder, Goslar, Göttingen, Groningen, Halberstadt, Halle, Hamburg, Hameln, Hanover, Hildesheim, Königsberg, Lübeck, Lüneburg, Magdeburg, Münster, Nimeguen, Osnabrück, Revel, Riga, Ruremonde, Stade, Stettin, Stralsund, Thorn, Venloo, Warberg in Sweden, Wesel, Wisby in the Isle of Gothland, Wismar, Zutphen, and Zwoll in Guelderland. Their four principal factories in foreign countries were at London, Bruges, Novgorod, and Bergen.

This powerful confederacy formed the first systematic plan of com. merce known in the middle ages. In its factories a discipline approaching in rigour that of the monasteries was observed, which even extended to the celibacy of factors, clerks, &c. The power of the Hansa rose daily. The cities enjoyed in England the privilege of exporting goods duty-free, and in Denmark of importing duty-free. Their alliance was courted and their hostility feared by the greatest powers. The Hanseatic League defeated kings Eric and Hakon, in Norway, and Waldemar III., king of Denmark, in 1348; they deposed Magnus, king of Sweden, and gave his crown to his nephew Albert, duke of Mecklenburg; they equipped in 1428 a fleet of 248 ships, with 12,000 soldiers on board, against Erick, king of Denmark; and the League concluded commercial treaties with Denmark, Flanders, and England, where Henry III., in 1266, granted them great immunities. But when the roads and seas were no longer insecure; when princes began to be sensible of the commercial interest of their own states; and above all, when the discovery of America, and the way to India by the Cape of Good Hope, gave an entirely new form and direction to commerce, the Hanseatic League gradually declined. On July 25, 1598, the lord mayor of London dispossessed them of the fleet-yard in the name of the queen, who had withdrawn their privileges, and at the last general assembly at Lübeck, the deputies from the several cities appeared merely to declare their secession from the League. Hamburg, Lübeck, and Bremen formed an association in 1614, and remained free republics till December, 1810, when they were incorporated with the French empire, but on the deliverance of Germany in 1813 they were again separated from France, and with Frankfort-on-the-Maine are now called the free Hanseatic Cities of the Germanic Confederation. For a particular account of their connection with England, see STEELYARD. There are numerous works treating of this league. In English, vol. i. of Anderson's Deduction of Trade and Commerce' may be consulted. In German, the most important works on the subject are F. Sartorius's "History of the German Hansa,' 3 vols., 1802-8, continued by Dr. J. M. Lappenberg, 2 vols., 1830-4; Die Urkundliche Geschichte des Hansische Stahlhofes,' zu London, 1851, containing much interesting matter relating to the Steelyard in Thames Street; and Mayer's 'Grosse Conversations Lexicon für die gebildeten Stände,' article 'Hansa,' contains a detailed history, with much of the internal constitution of the union.

HAQUEBUT. [ARMS.]

HARDNESS. A term applied to that condition of the force of

cohesion in solids where the constituent molecules retain their relative position and resist the application of a force which tends to change the figure of the body. [ATTRACTION.] Hardness is not the same quality as density, since many dense bodies are much softer than lighter ones. Thus glass is harder than gold or platinum, and platinum is harder and denser than gold. Iron and zinc are lighter but harder than gold and platinum. Lead is the softest of the common metals; but potassium and sodium can be moulded between the fingers like putty.

Language is quite inadequate to express the various degrees of hardness in solids. Accordingly the mineralogist resorts to the artifice of selecting a number of well-known minerals as standards of comparison. These are arranged in the form of a scale, known as the Scale of Hardness in which each mineral is harder than the one which precedes it, so that each mineral admits of being scratched or having its particles displaced by the one that follows it.

In determining the hardness of a body, if it neither scratch, nor is scratched by fluor-spar, for example, its hardness is said to be 4, but if it should scratch fluor-spar and not apatite, its hardness is between 4 and 5. The degrees of hardness are numbered from 1 to 10. The readiness with which some of the metals, steel especially, can be varied in hardness by heating, suddenly cooling, and then tempering, is of inestimable value in the useful arts. Another remarkable and useful property is in some cases developed in the production of alloys. Two metals, copper and tin for example, which are not separately remarkable for either hardness or elasticity, possess these properties in a high degree when combined in certain proportions, forming what is called bell-metal. [BELL-METAL.] Hardness is often accompanied by brittleness; but this may be lessened by heating and slow cooling, generally however at the expense of the hardness.

HARE-LIP, a malformation in which the lip is divided in one or more situations by clefts extending from its free edge towards its attachment. It has received this name from the resemblance which it bears to the divided upper lip of hares and other gnawing animals, and is one of the most common of the malformations by arrest of development. [MONSTER.] In the embryo, each lip is formed of four pieces which project separately from the jaws and unite with each other at different periods of foetal life; but if by any circumstance their healthy development is checked, they remain permanently in the condition which they had at the time of its occurrence. The separate portions of the lower lip unite long before those of the upper, and fissure of the former is so exceedingly rare as to be seldom the subject of treatment. Of the portions of the upper lip, the two middle unite first, and then the two lateral to them; hence a fissure in the middle line is more rare than one on either or each side. Hare-lip may be single or double; that is, there may be one or two fissures-the one may be seated in the middle line of the lip, or opposite to the union of the two incisors with the canine tooth: if there be two, they will be found in the latter situation on each side. It may be simple or complicated with fissures of the gum or palate, which, being developed in an analogous manner, may be influenced by the same cause as the lips, though being earlier united they are less rarely affected.

The cure of hare-lip is important, not only for the uncouth deformity, but because sucking is prevented in infancy, and in later life the speech is affected. It is accomplished by cutting off quite smoothly the opposite edges of the fissure in its whole length, and then bringing them together and maintaining them in accurate apposition till, like the edges of a common wound, they have firmly united. For this purpose, after fixing the portion of the lip with forceps, each edge of the fissure is to be cut off with a knife, or a pair of knife-edge scissors, taking especial care that the wounded surface should be left of the same form and size in each. They are then to be placed in accurate contact by transfixing them with one or two hare-lip pins (according to the length of the fissure), and connecting them with silk wound round them in the form of an 8. These pins should be made of silver, with removeable steel points; the lowest should be passed through full twothirds of the thickness of the lip, just above its vermilion border, taking care that it penetrates to the same depth in each portion, lest the edge of one should project beyond that of the other. The next pin should be passed midway between the lower edge of the lip and the nostril, and the remaining aperture should be closed with a suture or with sticking plaster. The intervening portions of the lip are now to be compressed by the silk wound about the pins, and additional security is afforded by placing a compress on each cheek, and there bandaging it firmly, so as to prevent the muscles of the lips from contracting and separating the cut edges. After the operation the part should be kept perfectly quiet and cool; in four or six days the pins and other dressings may be removed, and the edges of the wound, which ought to be completely united, will now need only to be secured by sticking-plaster.

When the fissure is double, it is generally advisable to operate first on one side, and when that is completely healed, on the other; but in some cases the whole may be done at once, by cutting off both edges of the middle and each of the lateral ones, and transfixing the whole by the same pins and sutures. In those cases in which a portion of the jaw-bone projects much, it may be sufficient to draw the teeth from it, and then the lip may be stretched to unite over it; but often it will be necessary to remove it by cutting-forceps, or to depress it by longcontinued pressure. In all cases it must be remembered, that however wide the fissures may be, there is no loss of substance in the lip; its edges are drawn asunder by the muscles on each side, just as are those of a cut made in a healthy lip (which may indeed require the very same treatment).

The best authorities seem now agreed that after six or eight weeks, the earlier this operation is performed on the infant the better, only avoiding the period of dentition; for besides that very young children