IIEM 



HEM 



%he tiller-rope, in all large vessels, is 

 wound about a wheel, which acts upon it 

 with the powers of a crane or windlass. 



There are several terms in the sea lan- 

 guage relating to the helm ; as " bear up 

 the helm ;" that is, let the ship go more 

 large before the wind : " helm a mid- 

 ship," or " right the helm ;" that is, keep 

 it even with the middle of the ship ; 

 *' port the helm," put it over the left side 

 of the ship : " starboard the helm," put 

 it on the right side of the ship. 



HELMET, an ancient defensive armour 

 worn by horsemen both in war and in 

 tournaments. It covered both the head 

 and face, only leaving an aperture in the 

 front secured by bars, which was called 

 the visor. It is still used in heraldry by 

 way of crest over the shield or coat of 

 arms, in order to express the different de- 

 grees of nobility by the different manner 

 in which it is borne. Thus, a helmet in 

 profile is given to gentlemen and esquires:' 

 to a knight, the helmet standing forward 

 and the beaver a little open : the helmet 

 in profile and open, with bars, belongs to 

 all noblemen under the degree of a duke : 

 and the helmet forward and open, with 

 many bars, is assigned to kings, princes, 

 and dukes. 



There is generally but one helmet up- 

 on a shield ; but sometimes there are two, 

 and even three; if there be two, they 

 ought to face each other ; and if three, 

 the middlemost should stand directly for- 

 ward, and the other two on the sides fac- 

 ing towards it. 



HELONIAS, in botany, a genus of the 

 Hexandria Trigynia class and order. Na- 

 tural order of Coronariae. Junci, Jussieu. 

 Essential character : calyx none ; corolla 

 six-petalled; capsule three-celled, There 

 are two species, viz. H. bullata, spear- 

 leaved helonias ; and H. asphodeloides, 

 grass-leaved helonias ; both natives of 

 North America. 



HEMEROBIUS, in natural history, a 

 genus of insects of the order Neuroptera. 

 Mouth with a short horny mandible, the 

 jaws cylindrical^straight, cleft ; feelers 

 -four, unequal, filiform ; wings deflected, 

 not folded ; antennae setaceous, project- 

 ing, longer than the thorax, which is con- 

 vex. There are nearly forty species, in 

 two divisions; A. lip cylindrical, mem- 

 branaceous, annulate : B. lip horny, 

 rounded at the tip, vaulted. The insects 

 belonging to this genus are, like the 

 ephemerae, very short-lived, and in every 

 slate of their existence prey, with un- 

 ceasing avidity, upon plant-lice. The 

 larva is six-footed, generally ovate and 

 hairy; the pupa mostly fQlliculute; the 



VOL. VL 



eggs are deposited in clusters on the 

 leaves of plants, each placed on a small 

 gummy pedicle. When touched, many of 

 them have an excrementitious smell. The 

 most common species is .the H. perla, an 

 insect of great beauty, seen chiefly in the 

 middle, and towards the decline of sum- 

 mer; and is a slender-bodied fly, of a 

 grass-green colour, with bright gold-co- 

 loured eyes, and four large, transparent 

 oval wings, finely reticulated with pale- 

 green veins. The eggs of this insect are 

 supported each one on a delicate stem, 

 of more than half an inch in length, which 

 is attached to the surface of a leaf or 

 twig, and by some persons, unacquainted 

 with their nature, they have been taken 

 for a small species of the fungus. From 

 the eggs are hatched the larva, which in. 

 a few days become fitted to undergo 

 their change into the chrysalis state. For 

 this purpose the animal draws a fine silk 

 from the extremity of the body, and in a 

 short space envelopes itself in a round 

 ball, of the size of a small pea, affixed to 

 a leaf or twig of the tree it frequents, 

 and divesting itself of its skin commences 

 a chrysalis ; in about three weeks it be- 

 comes a complete insect. The hemero- 

 bius takes its name from the shortness of 

 its life, as it seldom lives more than two or 

 three days. 



HEMEROCALLIS, in botany, English 

 day lily, a genus of the Hexandria Mono- 

 gynia class and order. Natural order cf 

 Lilia, or Liliaceae. Coronariae, Linnaeus. 

 Narcissi, Jussieu. Essential character: 

 corolla bell-shaped ; the tube cylindric ; 

 stamina declining. There are five spe- 

 cies. 



HEMIMERIS, in botany, a genus of 

 the Didynamia Angiospermia class and 

 order. Natural order of Personatae. Scro- 

 phulariae, Jussieu. Essential character : 

 calyx five-parted; corolla wheel-form; 

 upper lip cl6ven, with a nectareous bag 

 at the base. There are three species. 



HEMIONITES, in botany, English male 

 fern t a genus of the Cryptogamia Filices, 

 or Ferns. Generic character: capsules 

 digested into lines, meeting together, 

 either intersecting each other, or branch- 

 ed. There are eight species, natives of 

 both Indies. 



HEMISPHERE, in geometry, the half 

 of a globe or sphere, when it is suppos- 

 ed to be cut through its centre in the 

 plane of one of its great circles. Thus 

 the equator divides the terrestrial globe 

 into the northern a'nd southern hemis- 

 pheres : in the same manner the meridian 

 divides the globe into the eastern and 

 western hemispheres ; and the horizon 

 R 



