leader of an expedition to search for Eduard Vogel, his companions including Werner Munzinger, Gottlob Kinzelbach, and Dr Hermann Steudner. In June 1861 the party landed at Massawa, having instructions to go direct to Khartum and thence to Wadai, where Vogel was thought to be detained. Heuglin, accompanied by Dr Steudner, turned aside and made a wide detour through Abyssinia and the Galla country, and in consequence the leadership of the expedition was taken from him. He and Steudner reached Khartum in 1862 and there joined the party organized by Miss Tinné: With her or on their own account, they travelled up the White Nile to Gondokoro and explored a great part of the Bahr-el-Ghazal, where Steudner died of fever on the 10th of April 1863. Heuglin returned to Europe at the end of 1864. In 1870 and 1871 he made a valuable series of explorations in Spitsbergen and Novaya Zemlya; but 1875 found him again in north-east Africa, in the country of the Beni Amer and northern Abyssinia. He was preparing for an exploration of the island of Sokotra, when he died, at Stuttgart, on the 5th of November 1876. It is principally by his zoological, and more especially his ornithological, labours that Heuglin has taken rank as an independent authority.

His chief works are Systematische Übersicht der Vögel NordostAfrikas (1855); Reisen in Nordost-Afrika, 1852-1853 (Gotha, 1857); Syst. Übersicht der Säugetiere Nordost-Afrikas (Vienna, 1867): Reise nach Abessinien, den Gala-Ländern, &c., 1861-1862 (Jena, 1868); Reise in das Gebiet des Weissen Nil, &c. 1862-1864 (Leipzig, 1869); Reisen nach dem Nordpolarmeer, 1870-1871 (Brunswick, 1872-1874); Ornithologie von Nordost-Afrika (Cassel, 1869 1875); Reise in Nordost-Afrika (Brunswick, 1877, 2 vols.). A list of the more important of his numerous contributions to Petermann's Mitteilungen will be found in that serial for 1877 at the close of the necrological notice.

N

M

HEULANDITE, a mineral of the zeolite group, consisting of hydrous calcium and aluminium silicate, H1CaAl2(SiO3)6 +3H20. Small amounts of sodium and potassium are usually present replacing part of the calcium. Crystals are monoclinic, and have a characteristic coffin-shaped habit. They have a perfect cleavage parallel to the plane of symmetry (M in the figure), on which the lustre is markedly pearly; on other faces the lustre is of the vitreous type. The mineral is usually colourless or white, sometimes brick-red, and varies from transparent to translucent. The hardness is 3-4, and the specific gravity 2.2. Heulandite closely resembles stilbite (q.v.) in appearance, and differs from it chemically only in containing rather less water of crystallization. The two minerals may, however, be readily distinguished by the fact that in heulandite the acute positive bisectrix of the optic axes emerges perpendicular to the cleavage. Heulandite was first separated from stilbite by A. Breithaupt in 1818, and named by him euzeolite (meaning beautiful zeolite); independently, in 1822, H. J. Brooke arrived at the same result, giving the name heulandite, after the mineral collector, Henry Heuland. Heulandite occurs with stilbite and other zeolites in the amygdaloidal cavities of basaltic volcanic rocks, and occasionally in gneiss and metalliferous veins. The best specimens are from the basalts of Berufjord, near Djupivogr, in Iceland and the Faroe Islands, and the Deccan traps of the Sahyadri mountains near Bombay. Crystals of a brick-red colour are from Campsie Fells in Stirlingshire and the Fassathal in Tirol. A variety known as beaumontite occurs as small yellow crystals on syenitic schist near Baltimore in Maryland.

Isomorphous with heulandite is the strontium and barium zeolite brewsterite, named after Sir David Brewster. The greyish monoclinic crystals have the composition H.(Sr, Ba, Ca) Al2(SiO2)&+3H2O, and are found in the basalt of the Giant's Causeway in Co. Antrim, and with harmotome in the lead mines at Strontian in Argyllshire. (L. J. S.) HEUSCH, WILLEM, or GUILLIAM DE, a Dutch landscape painter in the 17th century at Utrecht. The dates of this artist's birth and death are unknown. Nothing certain is recorded of him except that he presided over the gild of Utrecht, whilst Cornelis Poclemburg, Jan Both and Jan Weenix formed the

council of that body, in 1649. According to the majority of historians, Heusch was born in 1638, and was taught by Jan Both. But each of these statements seems open to doubt; and although it is obvious that the style of Heusch is identical with that of Both, it may be that the two masters during their travels in Italy fell under the influence of Claude Lorraine, whose " Arcadian "art they imitated. Heusch certainly painted the same effects of evening in wide expanses of country varied by rock formations and lofty thin-leaved arborescence as Both. There is little to distinguish one master from the other, except that of the two Both is perhaps the more delicate colourist. The gild of Utrecht in the middle of the 17th century was composed of artists who clung faithfully to each other. Poclemburg, who painted figures for Jan Both, did the same duty for Heusch. Sometimes Heusch sketched landscapes for the battlepieces of Molenaer. The most important examples of Heusch are in the galleries of the Hague and Rotterdam, in the Belvedere at Vienna, the Städel at Frankfort and the Louvre. His pictures are signed with the full name, beginning with a monogram combining a G (for Guilliam), D and H. Heusch's etchings, of which thirteen are known, are also in the character of those of Both.

After Guilliam there also flourished at Utrecht his nephew, Jacob de Heusch, who signs like his uncle, substituting an initial J for the initial G. He was born at Utrecht in 1657, learnt drawing from his uncle, and. travelled early to Rome, where he acquired friends and patrons for whom he executed pictures after his return. He settled for a time at Berlin, but finally retired to Utrecht, where he died in 1701. Jacob was an Arcadian," like his relative, and an imitator of Both, and he chiefly painted Italian harbour views. But his pictures are now scarce. Two of his canvases, the " Ponte Rotto "at Rome, in the Brunswick Gallery, and a lake harbour with shipping in the Lichtenstein collection at Vienna, are dated 1696. A harbour with a tower and distant mountains, in the Belvedere at Vicína, was executed in 1699. Other examples may be found in English private galleries, in the Hermitage of St Petersburg and the muscums of Rouen and Montpellier.

HEVELIUS (HEVEL or HÖWELCKE], JOHANN (1611-1687), German astronomer, was born at Danzig on the 28th of January 1611. He studied jurisprudence at Leiden in 1630; travelled in England and France; and in 1634 settled in his native town as a brewer and town councillor. From 1639 his chief interest became centred in astronomy, though he took, throughout his life, a leading part in municipal affairs. In 1641 he built an observatory in his house, provided with a splendid instrumental outfit, including ultimately a tubeless telescope of 150 ft. focal length, constructed by himself. It was visited, on the 29th of January 1660, by John II. and Maria Gonzaga, king and queen of Poland. Hevelius made observations of sunspots, 16421645, devoted four years to charting the lunar surface, discovered the moon's libration in longitude, and published his results in Selenographia (1647), a work which entitles him to be called the founder of lunar topography. He discovered four comets in the several years 1652, 1661, 1672 and 1677, and suggested the revolution of such bodies in parabolic tracks round the sun. On the 26th of September 1679, his observatory, instruments and books were maliciously destroyed by fire, the catastrophe being described in the preface to his Annus climactericus (1685). He promptly repaired the damage, so far as to enable him to observe the great comet of December 1680; but his health suffered from the shock, and he died on the 28th of January 1687. Among his works were: Prodromus cometicus (1665); Cometographia (1668); Machina coelestis (first part, 1673), containing a description of his instruments; the second part (1679) is extremely rare, nearly the whole issue having perished in the conflagration of 1679. The observations made by Hevelius on the variable star named by him "Mira are included in Annus climactericus. His catalogue of 1564 stars appeared posthumously in Prodromus astronomiae (1690). Its value was much impaired by his preference of the antique" pinnules to telescopic sights on quadrants. This led to an acrimonious

"

controversy with Robert Hooke. In an Atlas of 50 sheets, corresponding to his catalogue, and entitled Firmamentum Sobiescianum (1690), he delineated seven new constellations, still in use. Hevelius had his book printed in his own house, at lavish expense, and himself not only designed but engraved many of the plates.

See J. H. Westphal, Leben, Studien, und Schriften des Astronomen Johann Hevelius (1820); C. B. Lengnich, Anekdoten und Nachrichten (1780); Allgemeine deutsche Biographie (C. Bruhns); J. B. J. Delambre, Histoire de l'astronomie moderne, ii. 471; J. F. Weidler, Historia astronomiae, p. 486; F. Baily's edition of the Catalogue of Hevelius, Memoirs Roy. Astr. Society, xiii. (1843); R. Wolf, Geschichte der Astronomie, p. 396; J. C. Poggendorff, Biog.-lit. Handwörterbuch. For an account of the epistolary remains of Hevelius, see C. G. Hecker, Monatl. Correspondenz, viii. 30; also Astr. Nachrichten, vols. xxiii., xxiv. (A. M. C.)

HEWETT, SIR PRESCOTT GARDNER, Bart. (1812-1891), British surgeon, was born on the 3rd of July 1812, being the son of a Yorkshire country gentleman. He lived for some years in early life in Paris, and started on a career as an artist, but abandoned it for surgery. He entered St George's Hospital, London (where his half-brother, Dr Cornwallis Hewett, was physician from 1825 to 1833) becoming demonstrator of anatomy and curator of the museum. He was the pupil and intimate friend of Sir B. C. Brodie, and helped him in much of his work. Eventually he rose to be anatomical lecturer, assistant-surgeon and surgeon to the hospital. In 1876 he was president of the College of Surgeons; in 1877 he was made serjeant-surgeon extraordinary to Queen Victoria, in 1884 serjeant-surgeon, and in 1883 he was created a baronet. He was a very good lecturer, but shrank from authorship; his lectures on Surgical Affections of the Head were, however, embodied in his treatise on the subject in Holmes's System of Surgery. As a surgeon he was always extremely conservative, but hesitated at no operation, however severe, when convinced of its expediency. He was a perfect operator, and one of the most trustworthy of counsellors. He died on the 19th of June 1891.

HEWITT, ABRAM STEVENS (1822-1903), American manufacturer and political leader, was born in Haverstraw, New York, on the 31st of July 1822. His father, John, a Staffordshire man, was one of a party of four mechanics who were sent by Boulton and Watt to Philadelphia about 1790 to set up a steam engine for the city water-works and who in 1793-1794 built at Belleville, N.J., the first steam engine constructed wholly in America; he made a fortune in the manufacture of furniture, but lost it by the burning of his factories. The boy's mother was of Huguenot descent. He graduated with high rank from Columbia College in 1842, having supported himself through his course. He taught mathematics at Columbia, and in 1845 was admitted to the bar, but, owing to defective eyesight, never practised. With Edward Cooper (son of Peter Cooper, whom Hewitt greatly assisted in organizing Cooper Union, and whose daughter he married) he went into the manufacture of iron girders and beams under the firm name of Cooper, Hewitt & Co. His study of the making of gun-barrel iron in England enabled him to be of great assistance to the United States government during the Civil War, when he refused any profit on such orders. The men in his works never struck-indeed in 1873-1878 his plant was run at an annual loss of $100,000. In politics he was a Democrat. In 1871 he was prominent in the re-organization of Tammany after the fall of the "Tweed Ring "; from 1875 until the end of 1886 (except in 1879-1881) he was a representative in Congress; in 1876 he left Tammany for the County Democracy; in the Hayes-Tilden campaign of that year he was chairman of the Democratic National Committee, and in Congress he was one of the House members of the joint committee which drew up the famous Electoral Count Act providing for the Electord Commission. In 1886 he was elected mayor of New York City, his nomination having been forced upon the Democratic Party by the strength of the other nominees, Henry George and Theodore Roosevelt; his administration (1887-1888) was thoroughly efficient and creditable, but he broke with Tammany, was not renominated, tan independently for re-election, and was defeated. In 1896

and 1900 he voted the Republican ticket, but did not ally himself with the organization. He died in New York City on the 18th of January, 1903. In Congress he was a consistent defender of sound money and civil service reform; in municipal politics he was in favour of business administrations and opposed to partisan nominations. He was a leader of those who contended for reform in municipal government, was conspicuous for his public spirit, and exerted a great influence for good not only in New York City but in the state and nation. His most famous speech was that made at the opening of the Brooklyn Bridge in 1883. He was a terse, able and lucid speaker, master of wit and sarcasm, and a fearless critic. He gave liberally to Cooper Union, of which he was trustee and secretary, and which owes much of its success to him; was a trustee of Columbia University from 1901 until his death, chairman of the board of trustees of Barnard College, and was one of the original trustees, first chairman of the board of trustees, and a member of the executive committee of the Carnegie Institution.

HEWLETT, MAURICE HENRY (1861- ), English novelist, was born on the 22nd of January 1861, the eldest son of Henry Gay Hewlett, of Shaw Hall, Addington, Kent. He was educated at the London International College, Spring Grove, Isleworth, and was called to the bar in 1891. From 1896 to 1900 he was keeper of the land revenue records and enrolments. He published in 1895 two books on Italy, Earthwork out of Tuscany, and (in verse) The Masque of Dead Florentines. Songs and Meditations followed in 1897, and in 1898 he won an immediate reputation by his Forest Lovers, a romance of medieval England, full of rapid movement and passion. In the same year he printed the pastoral and pagan drama of Pan and the Young Shepherd, shortened for purposes of representation and produced at the Court Theatre in March 1905, when it was followed by the Youngest of the Angels, dramatized from a chapter in his Fool Errant. In Little Novels of Italy (1899), a collection of brilliant short stories, he showed again his power of literary expression together with a close knowledge of medieval Italy. The new and vivid portraits of Richard Cœur de Lion in his Richard Yea-andNay (1900), and of Mary, queen of Scots, in The Queen's Quair (1904) showed the combination of fiction with real history at its best. The New Canterbury Tales (1901) was another volume of stories of English life, but he returned to Italian subjects with The Road in Tuscany (1904); in Fond Adventures, Tales of the Youth of the World (1905), two are Italian tales, and The Fool Errant (1905) purports to be the memoirs of Francis Antony Stretley, citizen of Lucca. Later works were the novel The Stooping Lady (1907), and a volume of poems, Artemision (1909).

HEXAMETER, the name of the earliest and most important form of classical verse in dactylic rhythm. The word is due to each line containing six feet or measures (uérpa), the last of which must be a spondee and the penultimate a dactyl, though occasionally, for some special effect, a spondee may be allowed in the fifth foot, when the line is said to be spondaic. The four other feet may be either spondees or dactyls. All the great heroic and epic verse of the Greek and Roman poets is in this metre, of which the finest examples are to be found in Homer and in Virgil. Varied cadences and varied caesura are essential to this form of verse, otherwise the monotony is wearying to the ear. The most usual places for the caesura are at the middle of the third, or the middle of the fourth foot: the former is known as the penthemimeral and the latter as hept hemimeral cacsura. There are several more or less successful examples of English poems in this metre, for example Longfellow's Evangeline, Kingsley's Andromeda and Clough's Bothie of Tober-naVuoilich, but it does not really suit the genius of the English language. In English the lack of true spondees is severely felt, even though the English metre depends, not, as in Greek and Latin, on the distinction between long and short syllables, but on that between accented and unaccented syllables. The accent must always (or it sounds very ugly) fall on the first syllable, whatever may have been the case in Greek and LatinVoss, Klopstock and Goethe have written hexameter poems

biting insects. In insects whose mouths are adapted for sucking and piercing, remarkable modifications may occur. In many bloodsucking flies, for example, the galea is absent, while the lacinia becomes a strong knife-like piercer and the palp is well developed.

In bugs and aphids the lacinia is a slender needle-like piercer (fig. 2, III), while the palp is wanting. In butterflies and moths the lacinia is absent while the galea becomes a flexible process, grooved on its inner face, so as to make with its fellow a hollow sucking-trunk, and the palp is usually very small.

The second pair of maxillae are more or less completely fused together to form what is known as the labium or "lower lip." In generalized biting insects, such as cockroaches and locusts (Orthoptera), the parts of a typical maxilla can be easily recognized in the labium. The fused cardines form a broad basal plate (sub-mentum) and the stipites a smaller plate (mentum)—sce fig. 1, C, sm, m-jointed on to the submentum, while the galeae, laciniae and palps remain distinct. In specialized biting insects, such as beetles (Coleoptera), the labium tends to become a hard transverse plate bearing the pair of palps, a median structure-known as the ligula-formed of the conjoined laciniae, and a pair of small rounded processes-the reduced galeae—often called the "paraglossae," a term better avoided since it has been applied also to the maxillulae of Aptera, entirely different structures. The long sucking "tongue" of bees is probably a modification of the ligula. In bugs and aphids (Hemiptera), the fused second maxillae form a jointed grooved beak or rostrum (fig. 2, IV) in which the slender piercers (mandibles and first maxillae) work to and fro.

Jaws.-The mandibles of the Hexapoda are usually strong jaws with one or more teeth at the apex (fig. 1, A, B, mn), articulating at their bases with the head-capsule by sub-globular condyles, and provided with abductor and adductor muscles by means of which they can be separated or drawn together so as to bite solid food, or seize objects which have to be carried about. They never bear seg. mented limbs (palps) and only exception ally (as in the chafers) is the skeleton composed of more than one sclerite. The mandibles often furnish a good example of "secondary sexual characters," being more strongly developed in the male than in the female of the same species. In most insects that feed by suction the mandi bles are modified. In bugs (Heteroptera) and many flies, for example, they are changed into needle-like piercers (fig. 2, II), while in moths and caddis-flies they are reduced to mere vestiges or altogether

IV

After Marlatt Entom. Bull. 14, n. s. (U.S. Dept. Agric.). suppressed.

As previously menFIG. 2.-Head of Cicad, front view. Ia, tioned, a pair of minute frons; b, clypeus (the pointed labrum jaws-the maxillulaebeneath it); II, mandible; III, first are present in the maxilla; (a, base; b, sheath; c, piercer); lowest order of insects, III', inner view of sheath; IV, second between the mandibles maxillae forming rostrum (b, mentum; and the first maxillae. ligula). They usually consist of an inner and an outer lobe arising from a basal piece, which bears also in some genera a small palp (see APTERA). In their typical state of development, the first maxillae offer a striking contrast to the mandibles, being composed of a two-segmented basal piece (cardo and stipes, fig. 1, C, ca, st) bearing a distinct inner and outer lobe (lacinia and galea, fig. 1. C. le, ga) and externally a

This second pair of maxillae (or labium) form then the hinder or lower boundary of the mouth. In front or above the mouth is bounded by the labrum, while the mandibles and first maxillae lie on either side of it. A median process, known as the hypopharynx or tongue, arises from the floor of the mouth in front of the labium, and becomes most variously developed or specialized in different insects. The salivary duct opens on its hinder surface. It does not appear to represent a pair of appendages, but the maxillulae of the Aptera become closely associated with it. According to the view of R. Heymons, the hypopharynx represents the sterna of all the jaw-bearing somites, but other students consider that it belongs to the mandibular and first maxillary segments, or entirely to the segment of the first maxillae.

Neck. The head is usually connected with the thorax by a distinct membranous neck, strengthened in the more generalized orders with small chitinous plates (cervical sclerites). These have been interpreted as indicating one or more primitive segments between the head and thorax. Probably, however, as suggested by T. H. Huxley (Anat. Invert. Animals, 1877), they really belong to the labial segment which has not become completely fused with the headcapsule. It has been shown by C. Janet (1889), from careful studies of the musculature, that the greater part of the head-capsule is built up of the four anterior head-segments, the hindmost of which has the mandibles for its appendages, and this conclusion is in the main supported by the recent work on the head skeleton of J. H. Comstock and C. Kochi (1902) and W. A. Riley (1904).

Thorax. The three segments which make up the thorax or foretrunk are known as the prothorax, mesothorax and metathorax (see fig. 3). The dorsal area of the prothorax is occupied by a single sclerite, the pronotum (fig. 3, d), which is large and conspicuous in those insects, such as cockroaches, bugs (Heteroptera) and beetles, which have the prothorax free-i.e. readily movable on the segment (mesothorax) immediately behind-smaller and of less importance where the prothorax is fixed to the mesothorax, as in bees and flies. The dorsal area of the mesothorax, and also of the metathorax, may be made up of a series of sclerites arranged one behind the other prescutum, scutum, scutellum and post-scutellum (fig. 3, e, f, g, h), the scutellum of the mesothorax being often especially conspicuous. Ventrally, each segment of the thorax has a sternum with which a median pre-sternum and paired episterna and epimera are often associated (see figs. 3, 4). The recent suggestion of K. W. Verhoeff (1904) that the hexapodan thorax in reality contains six primitive segments is entirely without embryological support.

Legs.-Each segment of the thorax carries a pair of legs. In most insects the leg is built up of nine segments: (1) a broad triangular, sub-globular, conical or cylindrical haunch (coxa); (2) a small trochanter; (3) an elongate stout thigh (femur); (4) a more slender shin (tibia); and (5-9) a foot consisting of five tarsal segments. The fifth (distal) tarsal segment carries a median adhesive padthe pulvillus-on either side of which is a claw. The pulvillus is