Man, a philosophical work, on the same ground as his first performance. 3. The Child of Nature improved by Chance, an indecent romance. (Watkins).

HELVOETSLUYS, a seaport of Holland, on the island of Voorn. It is the place of destination of the English packets from Harwich. Lat. 51. 45 N. Lon. 4. 23 E.

HEM. s. (hem, Saxon.) 1. The edge of a garment doubled and sewed to keep the threads from spreading (Wiseman.) 2. (hem men, Dutch.) The noise uttered by a sudden and violent expiration of the breath (Add.) 3. Interject. HEM! (Latin).

TO HEM. v. a. 1. To close the edge of cloth by a hem or double border sewed together. 2. To border; to edge (Spenser.) 3. to enclose; to environ; to confine; to shut (Fairfax).

To HEM. v. n. (hemmen, Dutch.) To utter a noise by violent expulsion of the breath.

HEMATITE, See HEMATITES. HEMERALOPIA. (hemeralopia, pa ia, from ημερινή a day, and ow, to see.) Crepusculary blindness. A defect of vision, in which the patient sees perfectly well all day, but in the crepusculary light, as in the evening, perceives little or nothing. It is often endemic to China, Barbadoes, the Brazils, and Poland. HEMERALOPS. (hemeralops, nepa, from, the day, and w, an eye). One who can see but in the daytime, or when the sun is in full strength.

HEMEROBAPTISTS, a sect among the ancient Jews, thus called from their washing and bathing every day in all seasons; and performing this custom with the greatest solemnity, as a religious rite necessary to salvation. Epiphanius, who mentions this as the fourth heresy among the Jews, observes, that in other points these heretics had much the same opinions as the Scribes and Pharisees; only that they denied the resurrection of the dead, in common with the Sadducees, and retained a few other of the improprieties of these last.

HEMEROBIUS. In zoology, a genus of the class insectæ, order neuroptera. Mouth with a short, horny mandible; the jaw cylindrical, straight, cleft; feelers four, unequal, filiform; without stemmata, or eyes on the crown; wings deflected, not folded; antennas setaceous, projecting, longer than the thorax, which is convex. Thirty-eight species; which may be thus subdivided:

A. Lip cylindrical, membranaceous, annulate; comprising the Fabrician tribe

semblis.

B. Lip horny, rounded at the tip, vaulted. Some of the different species are common to all the quarters of the globe: eight of them found in our own country. Like the ephemeræ, these insects are very short-lived; and in every state of their existence prey with unceasing avidity upon plant-lice: the larve is six-footed, generally ovate and hairy; the pupe mostly folliculate; the eggs are deposited in

clusters on the leaves of the plants, each placed on a small gummy pedicel. Many of the species when touched have an excrementitious smell. The colour varies much; that of the body is chiefly yellow, brown, or black, or intermixed, sometimes greenish: the wings are often white. Some of the species are smaller than the common louse; several of them resemble the termes, and perhaps might as well be included under that genus: whence the hemerobius of Fabricius comprises a whole tribe of the genus TERMES, which see. See also Nat. Hist. Pl. CXXXI.

HEMEROCALLIS. Day-lily. In botany, a genus of the class hexandria, order monogynia. Corol campanulate, with a cylindrical tube; calyxless; stamens declining. Four species; one a native of Switzerland, the other three of China and Japan.

1. H. flava. yellow day-lily or lily aspodel. Leaves linear; segments of the corol flat acute, with their nerves undivided. This is the Swedish plant.

2. H. fulva. Tanny day-lily; neres of the outer segments branched; a native of China.

3. H. lancifolia. Lance-leaved day-lily; leaves oblong, tapering to both ends, sevennerved.

4. H. Japonica, with roundish ovate leaves, pointed, many nerved. Indigenous to Japan, and producing in our own green-houses beautiful white flowers.

Of this last species there is also a beautiful variety, affording blue flowers. See Nat. Hist. Pl. CXXXV.

The two first are the most common, and obtained with most facility. Of these two the former is easily propagated by off-sets, which the roots send out in abundance; these may be taken off in autumn (that also being the best season for transplanting the roots) and planted in any situation; for, being extremely hardy, they will require no other culture than to be kept clean from weeds, and be allowed room to spread their roots. This sort may be propagated also by seeds, which, if sown in autumn, will produce plants the spring following, and these will flower in two years; but if the seeds be not sown till spring, the plants will not come up till the year after. The second species is usually propagated by parting the roots: the proper season for this is autumn, as also for transplanting the roots. These plants should not be transplanted oftener than every third year, when the roots may be parted to make an increase of the plants; but they must not be divided too small, for if they be, it will be two years before they flower. They delight in a light loamy seil, and an open exposure.

HEMERODROMI, compounded of mura, day, and p, course, &c. among the ancients, were sentinels or guards appointed for the security and preservation of cities and other places. They went out of the city every morning, as soon as the gates were opened, and kept all day patrolling round the

place; sometimes also making excursions farther into the country, to see that there were no enemies lying in wait to surprise them.

HEMERODROMI were also a sort of couriers among the ancients, who only travelled one day, and then delivered their packets or dispatches to a fresh man, who ran his day, and so on to the end of the journey.

HEMEROTROPHIS, in antiquity, a measure of capacity, the same with the choenix. It was so called from its holding one day's food. The word is compounded of pa a day, and food.

HEMI, a word used in the composition of various terms. It signifies the same with semi or demi, viz. half; being an abbreviature of mugs, hemisys, which signifies the same. The Greeks retrenched the last syllable of the word ημίσες in the composition of words; and after their example, we have done so too in most of the compounds borrowed from them. HEMICRANIA. (hemicrania, ninavia, from, half, and xpavi, the head). A pain that affects only one side of the

head.

HEMICYCLE, HEMICYCLIUM, in architecture, a term applied to semicircular vaults. HEMICYCLIUM was also a part of the orchestra in the ancient theatre. Scaliger, however, observes, it was no standing part of the ochestra; being only used in dramatic pieces, where some person was supposed to be arrived from sea, as in Plautus's Rudens. The ancients had also a sort of sun-dial, called hemicyclium. It was a concave semicircle, the upper end or cusp whereof looked to the north.

HEMIDITONE, in ancient music, the interval of a major-third diminished by half a tone: its constituting ratio is 5: 6.

HEMIMERIS. In botany, a genus of the class didynamia, order angiospermia. Calyx five-parted; corol wheel-shaped, reversed, gibbous at the base, cloven; filaments glabrous; capsule two-celled. Five species; three natives of the Cape, two of South America: all herbaceous plants; the two last with beautiful scarlet flowers.

HEMINA, formed of us, half, a vessel used as a measure among the ancient Romans, containing half the sextary. The hemina, called also cotyla, and acetabulum, contained eight ounces of liquor; and was about half our wine pint.

HEMIOBOLON, in antiquity, a weight of half the obolus, or five grains.

HEMIOLUS, or HEMIOLIA, among ancient musicians, denotes that ratio which we now call SESQUIALTERAL.

us, half, and w, an eye.) A defect of vision, in which the person sees the half, but not the whole of an object.

HEMIPLEGIA. (hemiplegia, jezdnying from us, half, and how, to strike). A paralytic affection of one side of the body. See PARALYSIS.

HEMIPTERA. In zoology, the second order of the class insecta consistently with the Linnéan system, thus ordinally characterised: mouth and snout beat in towards the breast; upper wings soft semi-crustaceous, not divided by a straight suture, the base of the left covering the inner margin of the base of the right. See ZOOLOGY.

HEMISPHERE. s. (n☛ paipiov.) The half of a globe, where it is supposed to be cut through its centre in the plane of one of its greatest circles (Dryden).

HEMISPHERES separated by different great circles on the mundane sphere are characterised by different names. Thus, the equator separates the northern and southern terrestrial hemispheres; the ecliptic, the northern and southern celestial hemispheres; the first meridian, the eastern and western hemispheres; and the horizon, the upper and lower hemispheres.

a

HEMISPHERES OF MAGDEBURGH, two brass concave hemispheres, one of which is furnished with a cock, by which it may be adjusted to the air-pump. The other has ring at the middle of its convexity, by means of which it may be suspended. When these two hemispheres are placed together, the air is drawn from within through the medium of the cock by the mechanism of the air-pump; and then, the exhaustion being carried far enough, and the cock turned to prevent the admission of air from without, a considerable force is requisite to separate the hemispheres: the force varying with their external surface This furnishes an easy and obvious method of proving the force and pressure of the air. Otto Guericke, the inventor of the air-pump, to whom also is due this invention, made hemispheres of about a foot radius, and found that the atmospheric pressure upon them was equivalent to about 5400 pounds.

HEMISPHERIC CALYX, or NECTARY. In botany. In form of half a sphere. The first exemplified in tanacetum : the second in narcissus jonquilla.

HEMISPHEROIDAL, in geometry, something that approaches to the figure of a hemisphere, but is not justly so.

HEMISTICH, compounded of quest half, and x, verse, in poetry, a half

verse.

Such, e. gr. are, Cernit Deus omnia vindexor Medio tutissimus ibis, &c.

HEMIOPSIA. (hemiopsia, muzofia, from

In English, &c. the common and Alexandrine verses require a rest at the end of each hemistich; common verses require it at