11-7-52 11-11-521 THE LONDON ENCYCLOPEDIA. them saw his own shadow projected upon it, and no other. The distance was such that all the parts of the shadow were easily distinguishable, as the arms, the leg, and the head; but what surprised them most was, that the head was adorned with a kind of glory, consisting of three or four small concentric crowns, of a very lively color, each exhibiting all the varieties of the primary rainbow, and having the circle of red on the outside. The intervals between these circles continued equal, though the diameters of them all were constantly changing. The last of them was very faint; and at a considerable distance was another great white circle, which surrounded the whole. As near as M. Bouguer could com pute, the diameter of the first of these circles was about 53°, that of the second 11°, that of the third 17°, and so on; but the diameter of the white circle was about 76°. This phenomenon never appeared but in a cloud consisting of frozen particles, and never in drops of rain like the rainbow. When the sun was not in the horizon, only part of the white circle was visible, as M. Bouguer frequently observed afterwards. Similar to this curious appearance was one seen by Dr. M'Fait in Scotland; who observed a rainbow round his shadow in the mist, when he was upon an eminence above it. In this situation the whole country round seemed buried under a vast deluge, and nothing but the tops of distant hills appeared here and there above the flood. In those upper regions, the air, he says, is at that time very pure and agreeable. At another time he observed a double range of colors round his shadow. The colors of the outermost range were broad and very distinct, and every where about two feet distant from the shadow. Then there was a darkish interval, and after that another narrower range of colors, closely surrounding the shadow, which was very much contracted. He thinks that these ranges of colors are caused by the inflection of the rays of light, the same that occasioned the ring of light which surrounds the shadow of all bodies, observed by M. Maraldi, and this author. HALO, or Corona, in optics, is a luminous circle surrounding the sun, moon, planets, or fixed stars. Sometimes these circles are white, and sometimes colored like the rainbow. Sometimes one only is visible, and sometimes several concentric halos appear at the same time. Those which have been seen about Sirius and Jupiter were never more than 3°, 4o, or 5° in diameter; those which surround the moon are, also, sometimes no more than 3° or 5°; but these, as well as those which surround the sun, are of very different magnitudes, viz. of 12° 0′, 22° 35′, 30° 0′, 38° 0′, 41° 2′, 45° 0′, 46° 24′, 47° 0′, and 90°, or even larger than this. Their diameters also sometimes vary during the time of observation, and the breadths both of the colored and white circles are very different, viz of 2°, 4°, or 7°. Their colors are more diluted than those of the rainbow; and they are in a different order, according to their size. Mr. Huygens observed red next the sun, and a pale blue outwards. Sometimes they are red on the inside and white on the outside. M. Weidler observed one that was yellow on the inside and white on the outside. In France one was observed, in 1683, the middle of which was white; after which followed a border of red, next to it was blue, then green, and the outermost circle was a bright red. In 1728 one was seen of a pale red outwardly, then followed yellow, and then green, terminated by a white. In Holland, M. Muschenbroeck says, fifty may be seen in the day-time, almost every year; but they are difficult to be observed, except the eye be so situated, that not the body of the sun, but only the neighbouring Halos may be produced by placing a lighted parts of the heavens, can be seen. Mr. Middle- candle in the midst of steam in cold weather. ton says, that this phenomenon is very frequent If glass windows be breathed upon, and the in North America; for that there is generally flame of a candle be placed some feet from it, one or two about the sun every week, and as while the spectator is also at the distance of some many about the moon every month. Halos feet from another part of a window, the flame round the sun are very frequent in Russia. M. will be surrounded with a colored halo. And if Epinus says, that from the 23d of April, 1758, to a candle be placed behind a glass receiver, when the 20th of September, he himself had observed air is admitted into the vacuum within it, at a cerno fewer than twenty-six, and that he has sometimes tain degree of density, the vapor with which it is seen twice as many in the same space of time. loaded will make a colored halo round the flame. This was observed by Otto Guericke. In December 1756 M. Muschenbroeck observed, that, when the glass windows of his room were covered with a thin plate of ice on the inside, the moon appearing through it was surrounded with Similar, in some respects, to the halo, was the remarkable appearance which M. Bouguer describes, as observed on the top of Mount Pichinca, in the Cordilleras. When the sun was just rising behind them, so as to appear white, each of VOL. XI.-PART I. B a large and variously colored halo; and, opening the window, he found that it arose entirely from that thin plate of ice, for none was seen except through it. Dr. Kotelnihow, having, like Dr. Halley, made very accurate observations to determine the number of possible rainbows, considers the colored halo, which appears about a candle, as the same thing with one of those bows which is formed near the body of the sun, but which is not visible on account of his excessive splendor. Descartes observes, that the halo never appears when it rains; from which he concludes that this phenomenon is occasioned by the refraction of light in the round particles of ice, which are then floating in the atmosphere; and, though these particles are flat when they fall to the ground, he thought they must be protuberant in the middle before their descent; and according to this protuberancy he imagined that the diameter of the halo would vary. In treating of meteors, Gassendi supposed, that a halo is of the same nature with the rainbow, the rays of light being in both cases twice refracted and once reflected within each drop of rain or vapor, and that all the difference there is between them arises from their different situation with respect to the observer. For whereas, when the sun is behind the spectator, and consequently the rainbow before him, his eye is in the centre of the circle; when he views the halo, with his face towards the sun, his eye is in the circumference of the circle; so that, according to the known principles of geometry, the angle under which the object appears, in this case, must be just half of what it is in the other. M. Dechales endeavours to show that the generation of the halo is similar to that of the rainbow. If, says he, a sphere of glass or crystal, full of water, be placed in the beams of the sun, there will not only be two circles of colored light on the side next the sun, and which constitute the two rainbows; but there will also be another on the part opposite to the sun, the rays belonging to which afterwards diverge, and form a colored circle, such as will be visible, if the light that is transmitted through the globe be received on a piece of white paper. The reason why the colors of the halo are more dilute than those of the rainbow, he says, is owing principally to their being formed not in large drops of rain, but in very small vapor; for, if the drops of water were large, the cloud would be so thick, that the rays of the sun could not be regularly transmitted through them; and, on the other hand, he observed, that when the rainbow is formed by very thin vapors, the colors hardly appear. As for those circles of colors which are sometimes seen round candles, it was his opinion that they are owing to nothing but moisture on the eye of the observer; for that he could never produce this appearance by means of vapor only, if he wiped his eyes carefully; and he had observed that such circles are visible to some persons and not to others, and to the same persons at one time and not another. The most considerable and generally received theory, respecting halos, is that of Huygens, published in the English Philosophical Transactions. See Lowthorp's Abridgment, Vol. II., p. 189. Sir Isaac Newton mentions it with respect. This article contains the heads of a discourse which he afterwards composed, but never quite finished; and which has been translated, with some additions, by Dr. Smith, from whom the following account is chiefly extracted. Mr. Huygens was first led to think particularly upon this subject, by the appearance of five suns at Warsaw, in 1658; after which, he says, he hit upon the true cause of halos and mock suns. If we can conceive any kind of bodies in the atmosphere, which, according to the known laws of optics, will, either by reflection or refraction, produce the appearance in question, when nothing else can be found that will do it, we must acquiesce in the hypothesis, and suppose such bodies to exist, even though we cannot give a satisfactory account of their generation. Two such bodies are assumed by M. Huygens; one of them a round ball, opaque in the centre, but covered with a transparent shell; and the other is a cylinder, of a similar composition. By the help of the former he endeavours to account for halos, and by the latter for those appearances which are called mock suns. Those bodies which M. Huygens requires, in order to explain these phenomena, are not, however, a mere assumption; for some such, though of a larger size than his purpose requires, have been actually found, consisting of snow within and ice without. They are particularly mentioned by Descartes. The balls with the opaque kernel, which he supposed to have been the cause of them, he imagines not to exceed the size of a turnip-seed. M. Marriotte accounts for the formation of the small coronas by the transmission of light through aqueous vapors, where it suffers two refractions without any intermediate reflection. He shows that light which comes to the eye, after being refracted in this manner, will be chiefly that which falls upon the drop nearly perpendicular; because more rays falling upon any given quantity of surface in that situation, fewer of them are reflected with small degrees of obliquity, and they are not so much scattered after refraction. The red will always be outermost in these halos, as consisting of rays which suffer the least refraction. And whereas he had seen, when the clouds were driven briskly by the wind, halos round the moon, varying frequently in their diameter, being sometimes of 2°, sometimes of 3°, and sometimes of 4°; sometimes also colored, sometimes only white, and sometimes disappearing entirely; he concluded that all these variations arose from the different thickness of the clouds, through which sometimes more and sometimes less light was transmitted. He supposed, also, that the light which formed them might sometimes be reflected, and at other times refracted. As to those coronas which consist of two orders of colors, he imagined that they were produced by small pieces of snow, which, when they begin to dissolve, form figures which are a little convex towards their extremities. Sometimes, also, the snow will be melted in different shapes; and, in this case, the colors of several halos will be intermixed and confused; and such, he says, he had sometimes observed round the sun. M. Marriotte then proceeds to explain the larger halos, viz. those that are about 45° in diameter, and for this purpose he has recourse to equiangular prisms of ice, in a certain position with respect to the sun; and he takes pains to trace the progress of the rays of light for this purpose; but this hypothesis is very improbable. In some cases he thought that these large coronas were caused by hailstones, of a pyramidal figure; because, after two or three of them had been seen about the sun, there fell the same day several such pyramidal hail-stones. M. Marriotte explains parhelia by the help of the same suppositions. See PARHE LION. M. Muschenbroeck concludes his account of coronas with observing, that some density of vapor, or some thickness of the plates of ice, divides the light in its transmission through the small globules of water, or their interstices, into its separate colors: but what that density was, or what was the size of the particles which composed the vapor, he could not determine. Sir Isaac Newton considered the larger and less variable appearances of this kind as produced according to the common laws of refraction, but that the less and more variable appearances depend upon the same cause with the colors of thin plates. He concludes his explication of the rainbow with the following observation on halos and parhelia :— The light which comes through drops of rain by two refractions, without any reflexion, ought to appear the strongest at the distance of about 26° from the sun, and to decay gradually both ways as the distance from him increases. And the same is to be understood of light transmitted through spherical hailstones: and if the hail be a little flatted, as it often is, the transmitted light may be so strong, at a little less distance than that of 26°, as to form a halo about the sun or moon; which halo, as often as the hail-stones are duly figured, may be colored, and then it must be red within by the least refrangible rays, and blue without by the most refrangible ones; especially if the hail-stones have opaque globules of snow in their centres to intercept the light within the halo, as Mr. Huygens has observed, and made the inside of it more distinctly defined than it would otherwise be. For such hail-stones, though spherical, by terminating the light by the snow, may make a halo red within, and colorless without, and darker within the red than without, as halos use to be. For, of those rays which pass close by the snow, the red-making ones will be the least refracted, and so come to the eye in the straightest lines.' Some farther thoughts of Sir Isaac Newton's on halos are subjoined to the account of his experiments on the colors of thick plates of glass which he conceived to be similar to those which are exhibited by thin ones: As light reflected by a lens quicksilvered on the back side makes the rings of the colors above described, so it ought to make the like rings in passing through a drop of water. At the first reflexion of the rays within the drop, some colors ought to be transmitted, as in the case of a lens, and others to be reflected back to the eye. For instance, if the diameter of a small drop or globule of water be about the th part of an inch, so that a red-making ray, in passing through the middle of this globule, has 250 fits of easy transmission within the globule, and ail the red-making rays, which are at a certain distance from this middle ray round about it, have 249 fits within the globules, and all the like rays at a certain farther distance round about it have 248 fits, and all those at a certain farther distance 247 fits, and so on, these concentric circles of rays, after their transmission, falling on a white paper, will make concentric rings of red upon the paper; supposing the light which passes through one single globule strong enough to be sensible, and in like manner the rays of other colors will make rings of other colors. Suppose now that in a fair day the sun should shine through a thin cloud of such globules of water or hail, and that the globules are all of the same size, the sun seen through this cloud ought to appear surrounded with the like concentric rings of colors, and the diameter of the first ring of red should be 7° 15', that of the second 10° 15′, that of the third 12° 33′, and, according as the globules of water are bigger or less, the ring should be less or bigger.' This curious theory our author informs us was confirmed by an observation which he made in 1692. He saw by reflexion, in a vessel of stagnating water, three halos, crowns, or rings of colors about the sun, like three little rainbows concentric to his body. The colors of the first or innermost, were blue next the sun, red without, and white in the middle, between the blue and red; those of the second crown were purple and blue within, pale red without, and green in the middle; and those of the third were pale blue within, and pale red without. These crowns enclosed one another immediately, so that their colors proceeded in this continual order from the sun outward; blue, white, red; purple, blue, green, pale yellow, and red; pale blue, pale red. The diameter of the second crown, mea sured from the middle of the yellow and red on one side of the sun to the middle of the same color on the other side, was 9° 33', or thereabouts. The diameters of the first and third he had not time to measure; but that of the first seemed to be about 5° or 6°, and that of the third about 12°. The like crowns appear sometimes about the moon: for in the beginning of the year 1664, on February 19th, at night, he saw two such crowns about her. The diameter of the first, or innermost, was about 3°, and that of the second about 5° 30′. Next about the moon was a circle of white; and next about that the inner crown, which was of a bluish green within, next the white, and of a yellow and red without; and next about these colors were blue and green on the inside of the outer crown, and red on the outside of it. At the same time there appeared a halo at the distance of about 22° 35' from the centre of the moon. It was elliptical; and its long diameter was perpendicular to the horizon, verging below farthest from the moon. told that the moon has sometimes three or more concentric crowns or colors encompassing one another next about her body. The more equal the globules of water or ice are to one another, the more crowns of colors will appear, and the He was colors will be the more lively. The halo, at the distance of 22° 30′ from the moon, is of another sort. By its being oval, and more remote from the moon below than above, he concludes that it was made by refraction in some kind of hail or snow floating in the air in an horizontal posture, the refracting angle being about 50° or 60°. Dr. Smith, however, makes it sufficiently evident, that the reason why this halo appeared oval, and more remote from the moon towards the horizon, is a deception of sight, and the same with that which makes the moon appear larger in the horizon. HALORAGUS, in botany, a genus of the tetragynia order and octandria class of plants: CAL. quadrifid above; there are four petals; a dry plum, and a quadrilocular nut. HALS'ENING, udj. Germ. hals; Scotch, Spenser himself affects the obsolete, Pope Sing harshly; inharmo- Halts on a quicksand, the first step ingulphs him. nious in the throat or tongue. Not in use. Halser, from Sax. þals neck, and yeel a rope. It is now in marine pronunciation corrupted to hawser. A rope less than a cable. The crueltee of thee, Quene Medea! Chaucer. Prologue to the Man of Lawe's Tale. Dryden. HALSTEAD, a market town of Essex, seated on a rising ground, on the Coln, forty-seven miles north-east of London. It has an old church, the steeple of which was once burnt down by lightning, but rebuilt at the expense of Robert Fiske, esq. The town consists of about 800 houses. The inhabitants manufacture says, bays, calimancoes, &c. There is a free school for forty boys, and a very antique Bridewell. Its market on Friday is noted for corn. HALT, v. n., adj. & n. s. Į Sax. pealt, lame; HALTER, n. s. Spealtan, to limp. To limp, or falter in walking; one who is disabled; a cripple; to stop suddenly as soldiers in a march; to doubt or hesitate; to be undecided; to fail or falter; in a religious sense, to backslide from former steadfastness. How long halt ye between two opinions? 1 Kings. All my familiars watched for my halting, saying, Peradventure he will be enticed, and we shall prevail against him. Jeremiah. Hill's Henry V. HALTER, n. s. & v. a. Sax. þealreɲe, from paly, the neck. A rope to hang malefactors; to bind with a cord; to catch in a noose. Whom neither halter binds nor burthens charge. Sandys. He's fled, my lord, and all his powers do yield; And humbly thus, with halters on their necks, Expect your highness' doom of life or death. Shakspeare. They were to die by the sword if they stood upon defence, and by the halter if they yielded; wherefore they made choice to die rather as soldiers than as dogs. Hayward. Were I a drowsy judge, whose dismal note Cleaveland. Dryden. He gets renown, who, to the halter near, Atterbury. HALTER-CAST is an excoriation of the pastern, occasioned by the halter's being entangled about a horse's foot, upon his endeavouring to rub his neck with his hinder feet. For the cure, anoint the place, morning and evening, with equal quantities of linseed oil and brandy, well mixed. HALTERISTE, in antiquity, a kind of players at discus. Some take the discus to have been a leaden weight or ball, which the vaulters bore in their hands, to secure and keep themselves the more steady in their leaping. Others say the halter was a lump of lead or stone, with a hole or handle fixed to it, by which it might be carried. Hier. Mercurialis, in his treatise De Arte Gymnastica, l. ii. c. 12, distinguishes two kinds of halterista; for, though there was but one halter, there were two ways of applying it. The one was to throw or pitch it; the other only to hold it out at arm's end, and in this posture to give themselves divers motions, swinging the hand backwards and forwards, according to the engraven figures thereof given us by Mercurialis. The halter was of a cylindrical figure, smaller in the middle, where it was held by one diameter, than at the two ends. It was above a foot long. and there was one for each hand: it was either of iron, stone, or lead. Galen, De Tuend. Vale tud. lib. i. v. and vi., speaks of this exercise, and shows of what use it is in purging the body of peccant humors, making it equivalent both to purgation and phlebotomy. HALVE, v. a. Dan. halv. See HALF. HALVES, interj. To divide equally: halves is an expression by which any one lays claim to an equal share. See HALF. Have you not seen how the divided dam Runs to the summons of her hungry lamb? But, when the twin cries halves, she quits the first. Cleaveland. HALYMOTE properly signifies a holy or ecclesiastical court. There is a halymote held in London, before the lord mayor and sheriffs, for regulating the bakers. It was anciently held on Sunday before St. Thomas's day, and hence called the haly mote, or holy court. HALYS, in ancient geography, the noblest river of the Hither Asia, through which it has a long course, was the boundary of Croesus's kingdom on the east. Running down from the foot of Mount Taurus, through Cataonia and Cappadocia, it divided almost the whole of the Lower Asia, from the sea of Cyprus down to the Euxine, according to Herodotus; who seems to extend its course too far. According to Strabo, who was a Cappadocian, it had its springs in Great Cappadocia. It separated Paphlagonia from Cappadocia, and received its name, arо rov aλoç, from salt, because its waters were of a salt taste, from the soil over which they flowed. It is famous for the defeat of Croesus, king of Lydia, who was misled by this ambiguous response of the oracle: Χροισος Αλυν διαβας μεγαλην αρχην diaλvou; i. e. If Cræsus passes over the Halys he shall destroy a great empire. That empire proved to be his own. See CREESUS. pressing them in a press eight or ten days, then steeping them in juniper water, and drying them by the smoke of juniper wood. A ham may be salted in imitation of those of Westphalia, by sprinkling a ham of young pork with salt for one day, to fetch out the blood; then wiping it dry, and rubbing it with a mixture of 1 lb. of brown sugar, lb. of saltpetre, pint of bay salt, and 3 pints of common salt, well stirred in an iron pan over the fire, till moderately hot; let it lie three weeks in this salting, turn it often, then dry it, and hang it up. Smoked hams,' says Dr. Willich, are a very strong food, which is not easily digested. If eaten in proper time, and in small quantities, they may be a cordial to some vigorous stomachs, especially in the morning, as a substitute for the pernicious hot and buttered rolls; but boiling renders their digestion still more difficult. See SMOKING. HAM, Heb. n, i. e. crafty. The youngest son of Noah, and father of Cush, Mizraim, Phut, and Canaan; each of whom possessed the countries peopled by them. Ham, it is believed, bad all Africa for his inheritance, and peopled it with his posterity. He himself, it is thought, dwelt in Egypt; but M. Basnage is of opinion, that neither Ham nor Mizraim ever were in Egypt, but that their posterity settled in this country, and called it by the name of their ancestor. He also doubts of his having been worshipped as a god, by the name of Jupiter Hammon. Be that as it may, Africa is called the Land of Ham in Psalm lxxviii. 51, cv. 23, cvi. 22. In Plutarch Egypt is called Chemia; and there are traces of the name of Ham or Cham in Psochemmis, and Psitta-chemmis, which are cantons of Egypt. See Egypt. HAMADAN, or AMADAN, a city of Irak, Persia, standing on or near the site of the ancient Ecbatana. It was taken and destroyed by Timur, and ever since has been only a secondary place. It contains, however, still 10,000 meanly built houses, and about 40,000 inhabitants. The wall which surrounded it was not long since destroyed. Hamadan is famous for its manufacture of leather, and is a considerable mart of commerce between Ispahan and Bagdad, and between the latter place and Tehraun. HAMADRYADES, from aua, together, and dpvc, an oak, a kind of inferior deities revered among the ancient heathens, and believed to preside over woods and forests, and to be enclosed under the bark of oaks. They were supposed to live and die with the trees they were attached to, as is observed by Servius on Virgil, Eclog. x. v. 62, after Mnesimachus, the scholiast of Apollonius, &c., who mentions other traditions relating to them. The poets often confound the Hamadryads with the Naiads, Napææ, and rural nymphs in general. Festus calls them Querquetulanæ, as being sprung from oaks. Pherenicius, in Athenæus, lib. iii. calls the vine, fig-tree, and other fruit trees, hamadryades. This idea among the ancients, of intellectual beings annexed to trees, accounts for their worship of trees. Livy speaks of an ambassador addressing himself to an old oak, as to an intelligent person and a divinity.-Lib. iii. § 25. HAMAH, a town of Asiatic Turkey, in Syria, |