of the Product and Powers of Numbers" (London, 1781); "Mathematical Tables (1785); (1785); "Course of Mathematics" (3 vols., 1793); and "Mathematical and Philosophical Dictionary (2 vols. 4to, 1795). He was also for many years editor of the "Ladies' Diary." | HUTTON, James, a British natural philosopher, born in Edinburgh, June 3, 1726, died March 26, 1797. He entered the university of Edinburgh in 1740, and began the study of law, which he subsequently abandoned for medicine, taking the degree of M. D. at Ley-vancement of science. From 1870 to 1872 he den in 1749. He engaged in the manufacture of sal ammoniac from coal soot, inherited from his father a small estate in Berwickshire, betook himself to agriculture, finally removed to his native city in 1768, devoting himself especially to the study of geology, and made several important discoveries. In 1795 he pub-ing, and particularly by his denunciation of the lished the results of 30 years' study in his "Theory of the Earth," assuming that heat is the principal agent of nature. HUXLEY, Thomas Henry, an English naturalist, born in Ealing, Middlesex, May 4, 1825. He spent two and a half years at Ealing school, in which his father was one of the masters, but with this exception his education was carried on chiefly at home. In 1842 he entered the medical school of Charing Cross hospital, and in 1845 received the degree of M. B. from the university of London, being placed second in the list of honors for anatomy and physiology. He began his literary career while yet a student by contributing to the "Medical Times and Gazette a paper on that layer in the root sheath of hair which has since borne his name. In 1846 he joined the medical service of the royal navy, and was stationed at Haslar hospital, whence he was selected the same year to accompany Capt. Stanley, as assistant surgeon of the Rattlesnake, in his expedition to the South Pacific. After a four years' voyage of circumnavigation, during which surveys of the east coasts of Australia and Papua were made, the ship returned to England in November, 1850. While absent Mr. Huxley, who made extensive observations on the natural history of the seas traversed, sent home a number of communications, the first of which, read before the royal society in 1849, is "On the Anatomy and Affinities of the Family of the Medusa." On his return some of these papers were elaborated by him and published in the "Philosophical Transactions" of the royal society, of which, in June, 1851, he was elected a fellow. In 1853 he resigned his position in the navy, and in the following year he succeeded Prof. Edward Forbes as professor of natural history in the royal school of mines, an office which he still holds (1874). He has since resided in London, where he has devoted himself to constant scientific labor and research. In addition to his annual course of lectures on general natural history, he has delivered many lectures on kindred subjects to mixed audiences, and has done much to popularize sci ence. He was Hunterian professor in the royal college of surgeons from 1863 to 1869, and was twice chosen Fullerian professor of physiology in the royal institution. In 1869 and 1870 he was president both of the geological and the ethnological society; in 1870 he was president of the British association for the advancement of science; and in 1872 he became secretary of the royal society. Since 1870 he has been a member of the royal commission on scientific instruction and the adserved on the London school board, where he was chairman of the committee which drew up the scheme of education adopted in the board schools. During this time he took an active part in its deliberations, and became conspicuous by his opposition to denominational teachdoctrines of the Roman Catholic church. In 1872 he was elected lord rector of the university of Aberdeen.-Prof. Huxley has done as much probably as any living investigator to advance the science of zoology, and the world is indebted to him for many important discoveries in each of the larger divisions of the animal kingdom. His earlier labors were devoted chiefly to the lower marine animals, with which he formed a most thorough empirical acquaintance during his Pacific voyage, and he has described many which previously had been either unknown or very imperfectly studied. During the past ten years he has devoted himself assiduously to the comparative anatomy and the classification of the vertebrata, and has embodied the results of his more important researches in numerous monographs. In his first published work, on the medusæ, he called attention to the fact that the body of these animals is formed of two cell layers, which may be compared to the two germinal layers of the higher animals; an idea which has since found its complete expression in the gastræa theory of Haeckel. To him also is due the vertebral theory of the skull, which has since been demonstrated so clearly by Gegenbaur; and he was the first to extend to man Darwin's theory of natural selection. In his three lectures on "Man's Place in Nature," delivered in 1863, he made an elaborate exposition of the doctrine of evolution as applied to man, asserting that the anatomical differences between man and the highest apes are of less value than those between the highest and the lowest apes. Among his many popular lectures, that "On the Physical Basis of Life," delivered in 1868, has attracted much attention. In it he advances the idea that there is some one kind of matter common to all living beings; that this matter, which he designates as protoplasm, depends on the preëxistence of certain compounds, carbonic acid, water, and ammonia, which when brought together under certain conditions give rise to it; that this protoplasm is the formal basis of all life, and therefore all living powers are cognate, and all living forms, HUY, a town of Belgium, in the province and 16 m. S. W. of the city of Liége, at the entrance of the Hoyoux into the Meuse; pop. in 1866, 11,055. It has a handsome Gothic church, a college, manufactories of paper, leather, and faience, distilleries, and an active trade. The former abbey of Neufmoutier contained the tomb of Peter the Hermit, by whom it had been founded; in 1858 a statue was erected in his honor in the garden of the abbey. In the neighborhood there are mines of iron, zinc, and coal, and several mineral springs. from the lowest plant or animalcule to the | had already written upon the subject, but the highest being, are fundamentally of one char- treatise of Huygens was more profound, and acter. Prof. Huxley is a corresponding mem- 50 years afterward James Bernoulli employed ber of the principal foreign scientific societies, it as an introduction to his Ars Conjectandi. and has received honorary degrees from the It was also translated into Latin by his former universities of Breslau and Edinburgh. His tutor Schooten under the title De Ratiociniis works are as follows: "The Oceanic Hydro- in Ludo Alex, by which it is also known in zoa" (1857); "Evidence as to Man's Place in 's Gravesande's edition of Huygens's works. Nature" (1863); "Lectures on the Elements Schooten published it in his Exercitationes of Comparative Anatomy" (1864); "Lessons Mathematica, to demonstrate, as he says, the in Elementary Physiology" (1866); "An In- utility of algebra. About this time Huygens troduction to the Classification of Animals" sent a paper to Wallis on the area of the cis(1869); "Lay Sermons, Addresses, and Re- soid, and to Pascal a calculation for hyperbolic views" (1870); and "Critiques and Address- conoids, and spheroids in general, and on the es" (1873). He is the author also of a large quadrature of a portion of a cycloid, in which number of papers published in the journals papers he employed methods having the highof the royal, the Linnæan, the geological, and est characteristics of original thought. But the zoological societies, and in the memoirs of his attention was not wholly devoted to merethe geological survey of Great Britain. ly theoretical mathematics, for about this time he introduced one of the most practical and important of all inventions. Galileo had observed the isochronism of small vibrations of the pendulum, and had employed it as a measurer of time, but his method required an assistant to count the oscillations, and was of course far from being exact. To keep the pendulum in motion and cause it to register its successive vibrations was one of the problems which Huygens attempted, and which he succeeded in solving by the invention of the pendulum clock, a description of which, under the title of Horologium, he dedicated to the states general of Holland in 1658. (See CLOCKS AND WATCHES.) In 1659 he constructed a telescope of 22 ft. focal length, in which he used a combination of two eye pieces, and again examined Saturn, making the discovery of the ring of the planet. The singular appearance which it sometimes presents of being accompanied by two luminous bodies, one on either side, had been observed by Galileo, but his telescope had not sufficient power to permit him to discover its cause. Huygens's instrument enabled him to make out that the phenomenon in question, which at regular times appeared and disappeared, was produced by the oblique position of the ring with regard to the earth and to the sun. From an analysis of the phenomenon he predicted the disappearance of the ring in 1671, and the prediction was verified. He published an account of these observations at the Hague in 1659, in a volume also containing an account of several other discoveries, such as that of the great nebula in the sword of Orion, the bands upon the disks of Jupiter and Mars, and the fact that the fixed stars have no sensible magnitude. It was also accompanied by a description of a method for measuring the diameter of the planets. The micrometer used by him has been superseded by others, but it served the purpose of making correct measurements. 1660 he visited France and England, and soon after published his celebrated theorems on the laws of the impact of bodies, in which most of the principles of the laws of motion are es HUYGENS (incorrectly HUYGHENS), Christian, a Dutch natural philosopher, born at the Hague, April 14, 1629, died there, July 8, 1695. He was the second son of Constantine Huygens, secretary and counsellor of the stadtholders Frederick Henry, William II., and William III. His father taught him the rudiments of education and the elements of mechanics. At the age of 15 he became the pupil of Stampion, and at 16 he was sent to Leyden to study law with Vinnius, who dedicated to him his first commentary on the Institutes of Justinian. He there also pursued mathematical studies, and afterward at Breda in the university, which was under the direction of his father. In 1650, after a journey to Denmark with Henry, count of Nassau, he began those mathematical and physical researches which afterward made him famous. In 1651 he published at Leyden his first work, on the quadrature of the hyperbola, the ellipse, and the circle, and in 1654 a paper entitled De Circuli Magnitudine inventa nova. In 1655 Huygens went for the first time to France, and received the degree of doctor of laws from the faculty of the academy of Angers. On his return to Holland he turned his attention to the construction of telescopes, in connection with his elder brother Constantine. With one of these instruments, having a focal length of 10 ft., and more powerful than any ever before made, he discovered the first (now called the fourth) satellite of Saturn, and published the discovery at the Hague in 1656. During the next year he wrote a paper on the calculus of probabilities. Pascal and Fermat In tablished. In 1665, at the invitation of Col- | had proposed as a test to the followers of the bert, he went to France and became a mem- old methods the problem of finding the curve ber of the academy of sciences, then recently of equable approach, or that which a susformed. Apartments were assigned to him in pended body must follow in order to approach the royal library, and he resided in Paris for the or recede from equal heights in equal times. greater part of the next 15 years, during which Huygens accomplished the solution by the old time he presented many papers to the acade- methods, but he was the only one who sucmy, some of which still remain unpublished | ceeded. Soon after this Newton published in its archives. In 1670 he visited Holland to his Principia, and Huygens, with a desire of restore his health, which had become impaired becoming acquainted with the author, visited by his great labors; and on his return to Paris England for the third time, and on his return in the following year he completed his great published his treatise on light under the title work Horologium Oscillatorium (fol., Paris, Traité de la lumière, où sont expliquées les 1673). To this book are appended 13 theorems causes de ce qui lui arrive dans la réflexion, on centrifugal force, which will be noted fur- dans la réfraction et particulièrement dans ther on. About this time he invented the | l'étrange réfraction du cristal d'Islande (Leyspiral spring which is applied to the balance den, 1690). Soon after this he investigated wheel of watches, a description of which was the properties of the catenary curve, a problem published in the journal of the academy of sci- which had just been proposed by James Berences in 1675. The invention was claimed by noulli, who had become proficient in the methHooke of England and Hautefeuille of France, ods of the differential calculus; but Huygens but the evidence that it is the invention of Huy- solved the question by the old methods, which gens is too strong to be any longer questioned. was considered a wonderful achievement. He It is said that the first watch provided with a nevertheless found the task so difficult that hair spring was made by Thuret under Huy- his opposition to the differential calculus was gens's direction, and was sent to England. In shaken, and he entered at once into corre1675 he again went to Holland for the benefit spondence with Leibnitz. He had previously, of his health, and in 1676 he read before the whenever meeting with difficulties, attributed academy of sciences his famous treatise on them to himself and not to defects in the light, and also a treatise on the cause of grav- methods. After examining the differential ity, in which he attempts to account for the calculus he admitted its superiority, immeforce by supposing that ethereal matter revolves diately commenced its use, and soon gave a about the earth with a velocity greater than wider development to the invention than it that of the planet, and compares it to the force had yet attained. At his death he left his which causes bodies a little heavier than wa- manuscripts to the library of Leyden, intrustter, and lying lightly upon the smooth bottom ing their publication to two of his pupils, Volof a cylindrical vessel containing water, to der and Fullen.-Huygens was never married, move toward the centre when the circular mo- and aside from his scientific pursuits his life tion of the vessel by which its fluid contents was not eventful. He had a fine personal aphave been caused to revolve is arrested. In pearance, and his character was eminently 1681 he returned to his native country, and noble. Newton spoke of him as the summus immediately began the construction of an au- Hugenius, and considered his style as an automatic planitarium to represent the true mo- thor more classic than that of any other mathetion of the bodies of the solar system. This matician of that time. He was affable and invention led to the important discovery of kind, and was easily accessible to young stucontinued fractions, which he found it neces- dents, whom he was always delighted to assist sary to employ in order to establish the rela- in their investigations. His labors were imtion between the number of teeth contained in mense, and the practical value of their results two wheels which play into one another. is inestimable. His discovery of the laws of After this he resumed for several years, in the double refraction of light in Iceland spar, conjunction with his brother Constantine, the and of polarization, perhaps as much as any construction of telescopes. He made two ob- other cause, led to the reëxamination of the jectives, one of 170 and another of 210 ft. undulatory theory, and, with the necessary focal length, which he presented to the royal adaptations, to its employment to account for society of London. As a telescope of such di- all the phenomena of radiation of both heat mensions would be difficult to manage, Huy- and light. In accordance with this theory the gens proposed to dispense with the tube and most important researches in modern physics place the object glass in an elevated position have been made, as those upon the diatherso that it could be adjusted to any angle, and manous properties of bodies, and upon the abthen to place the eye piece at the focus. This sorption of radiant heat by gases and vapors, arrangement continued to be used until the by which great light has been thrown on the introduction of reflecting telescopes. While science of meteorology. Besides his invention Huygens was absorbed in these occupations a of the pendulum clock and of the balance great revolution was going on in the mathemat- wheel to the watch, the first chronometers ical world. Leibnitz had invented the differ- taken aboard ships were made under his direcential calculus, which he published in 1684, and tion, and he was far in advance of all others the flower cluster has been greatly increased, the flowers are semi-double and double, and there is a great variety of colors and tints, from pure white, through various shades of red and blue, to nearly black. The number of named varieties is very large, and includes not only self-colored ones, but double and single kinds, with flowers variously striped and shaded. The bulb growers near Haarlem in Holland supply the world with hyacinths, which form a large share of what are imported under the name of "Dutch bulbs." The eminence of the Dutch florists in the culture of this and other bulbs is in part due to a favorable soil and climate, and in part to the patient care given to their cultivation; these, with the low price of labor, have enabled them to hold a monopoly of bulb growing. Near Haarlem over 100 acres of land are annually devoted to hyacinths; the soil is a mixture of sand and alluvium, and permanently supplied with the requisite moisture. New varieties are obtained by sowing seed, and it is necessary to cultivate the seedlings for six years before their real of his day in astronomical observations. His discovery of the isochronism of the cycloid was one of the most important in mathematics; and not inferior to it is the invention of the involution and evolution of curves, and the establishment of the proposition that the cycloid is its own evolute. He also, in his Horologium Oscillatorium, gives a method for finding the centre of oscillation, which was the first successful solution of a dynamical problem in which connected material points are supposed to act on one another. The difficulty of this subject is shown by the fact that Newton fell into an error in regard to it in attempting to solve the problem of the precession of the equinoxes. The question of the centre of oscillation had been proposed by Mersenne in 1646, and although some cases had been solved on the principle of the centre of percussion, it was beyond the reach of any methods then known. Huygens was only a boy of 17 when the question was proposed, and could then see no principle by which it could be solved; but when he published his Horologium Oscillatorium in 1673, the principles which he assumed led to correct results in all cases. The two first theorems appended to that work state: 1, that if two equal bodies move in unequal circles in equal times, the centrifugal forces will be proportional to the diameters of the circles; and 2, that if the velocities are equal, the centrifugal forces will be in the inverse ratio of the diameters. To arrive at these conclusions required the application of the second law of motion (i. e., that the motion which a force gives to a body is compounded with the motion which it previously had) to the limiting elements of the curve, in the manner in which Newton afterward demonstrated the theorems of Huygens in his Principia. Huygens's own demonstrations of these theorems were found after his death among his papers. In his treatise on the impact of bodies (De Motu Corporum ex Percussione), Huygens must have assumed the third law of motion, which Newton afterward expressed by saying that "action and reaction are equal and opposite," by which we understand that the quantity of motion in the impact of bodies remains unchanged, one of the first grand principles in the doctrine of the conservation of force. His works were edited by 's Gravesande under the titles of Opera varia (2 vols. 4to in 1, Leyden, 1724) and Opera Reliqua (2 vols. 4to, Amsterdam, 1728). HYACINTH, a genus of liliacea, containing several species, the most important of which is hyacinthus orientalis, a native of the Levant. This has an onion-like bulb, which throws up long, narrow-channelled leaves, from among which arises a scape bearing a raceme of bellshaped drooping flowers; the parts of the perianth are united to about the middle, and the free portions reflexed; flowers often very fragrant, appearing in early spring. This being one of the florists' flowers, great changes have been produced in it by cultivation; the size of merit can be decided upon. Established varieties are multiplied from the small bulbs which form at the base of the larger ones; a bulb will naturally produce several of these, and the cultivators increase the number by wounding and cutting the bulb in various ways. The small bulbs are carefully cultivated until of a proper size for market; in order to increase its size as rapidly as possible, the bulb is not allowed to exhaust its strength in producing flowers, but the flower stem is cut away as soon as it appears. Millions of bulbs are annually imported into this country and England, and large quantities go to other countries. The best are imported by the dealers direct from the growers; it is only the poorer bulbs, from which the finer ones have been selected, that are usually offered at auction. The different varieties are put up in bags of heavy paper, with an abundance of the hulls of buckwheat, and the bags are packed in cases. The heaviest bulbs, which show no signs of decay by being soft at the top, are to be preferred. Named sorts cost much more than assorted kinds, which for the general cultivator may be quite as satisfactory as those with names. The bulbs for outdoor culture are usually planted in October. A rich light soil is best, and well decomposed cow manure is the best fertilizer; the bulbs should be set 8 in. apart and covered to the depth of 4 in.; when cold weather comes on, the bed is to be covered with litter, which is to be left on until spring; when the plants come into flower each spike will need the support of a small stick or wire, which may be so placed as not to be noticed; when the flowers decay their stalks are cut away, and the bulbs allowed to remain until the fading of the leaves shows that they have Sinished their growth; they are then taken up, dried in the sun, each wrapped in a paper with its label, and kept in a cool dry place until time to plant in autumn. They do not bloom in subsequent years so well as the first. In some gardens the bulbs are left Hyacinth (Hyacinthus orientalis). English Bluebell. from year to year; they increase and form large clumps, which produce small spikes of flowers. The hyacinth is an easy plant to force in the greenhouse or in an ordinary room; the bulbs should be potted in October, and the pots placed in a cool dark cellar, or in a shady corner, and covered with coal ashes; when an inspection of the pots shows that the ball of earth is well filled with roots, they may be. brought to a warm and light place, when growth of leaves and flowers will soon commence; frequent failure is due to not first securing a good growth of roots by keeping the bulb cool and from the light. The bulbs are often forced in glasses made for the purpose, filled with water; the base of the bulb should just touch the surface of the water, and the glass should be kept in the dark until the roots are well developed. Bulbs that have been forced are of little value; single varieties are preferred for forcing.—The wild hyacinth, the bluebell of England, H. nonscriptus of the older botanists, has been successively placed in several different genera, and is probably nearer a squill (scilla) than a hyacinth. HYACINTHE, Père. See LOYSON, CHARLES. HYACINTHUS, in Greek mythology, son of the Spartan king Amyclas and Diomede, or of Pierus and Clio, or of Ebalus and Eurotas. He was a boy of great beauty and the favorite of Apollo, but was also beloved by Zephyrus, who from jealousy caused his death as he was playing with Apollo, by blowing the quoit of the god against his head. From his blood sprang the flower hyacinth, upon whose leaves appears the Greek exclamation of woe AI, AI, or the letter Y beginning his name ("Táкiv0os). HYADES, in Greek mythology, nymphs variously described as being from two to seven in number, and bearing 18 names. According to some authorities, Jupiter placed them among the stars in honor of their care of the infant Bacchus; while others say it was to reward them for their long mourning for their brother Hyas, who had been killed by a wild boar. HYENA, a digitigrade carnivorous mammal, most numerous in Africa, but found also in southern and middle Asia, where the genus has probably spread while following the track of armies and caravans. Zoölogists are not agreed as to the position of this animal; the older authors place it in the feline family, with which it agrees in the single true molar on each side of both jaws, and in the single tuberculate tooth on each side of the upper jaw only; Waterhouse regarded it as a small divergent group of viverrina or civet cats; Linnæus ranked it in his genus canis; and Hamilton Smith puts it in juxtaposition to the dogs. It seems to be an osculant type, united on the · one hand to the dogs by the genus lycaon, and on the other to the civets by the genus proteles (aard-wolf); its general aspect is decidedly canine, as also are most of its habits. The dental formula, according to Owen, is: incisors, canines, premolars, 4, and molars 11-34 in all. The disposition of the hyæna is fierce and cowardly, and its habits are revolting; it is able to withstand any temperatures and priva |