HAS 



HE A 



on the one hand, and soft chalk on the 

 other, 



HARMO'NICON, CHEMICAL. An 

 apparatus for imparting a sonorous pro- 

 perty to the air. If a small flame of hy- 

 drogen gas be made to burn in a tube of 

 glass or of any other material, of from 

 one to three inches in width, the column 

 of air contained in the tube will in a 

 short time be heard to give forth musical 

 sounds. These are occasioned by the 

 combustion of the hydrogen in the atmo- 

 spheric air contained in the tube, and 

 thus an influx of the surrounding atmo- 

 sphere is produced. The sounds are 

 heard when the flame of the hydrogen 

 becomes small and steady. 



HARMO'NICS {apfjLovia, concord). 

 The doctrine of harmonical combinations 

 in music, as they occur in the natural 

 series, 1, 2, 3, 4, &c. Thus, the first 

 interval, 1 I 2, is an octave ; the second, 

 1 : 3, is a twelfth ; the third, 1 I 4, is a 

 fifteenth; the fourth, 1 ; 5, a seven- 

 teenth ; the fifth, 1 : 6, a nineteenth; 

 &c. 



HA'RMONY {apfjLovia, concord). A 

 combination of sounds, forming a mu- 

 sical chord, or a succession of chords. 

 The harmonic triad, or common chord, 

 consists of a note, with its third and 

 perfect fifth, and is the result of the 

 vibration of all sonorous bodies. 



HA'RMOTOME {apiJi6<!, a joint, rofxr], 

 a section). A silicate of barytes and 

 alumina, containing water, found at An- 

 dreasberg in the Hartz : the crystals of 

 this mineral intersect one another length- 

 wise, and are easily separable. It is also 

 called staurolite, or cross stone. 



HARPA'LlDiE. A family of Coleo- 

 pterous insects of the section Geodephaga, 

 named from the genus Harpalus, dis- 

 tinguished by the tarsi of the two ante- 

 rior pairs of legs being dilated in the 

 male sex. 



HARVEST and HUNTERS' MOON. 

 Twice in the year the moon rises almost 

 at the same hour during a week. This 

 occurs in September or October, and in 

 March or April : in the former case the 

 moon is termed the harvest moon, in the 

 latter the hunters' moon. 



HA'STATE {hastatus, spear-shaped). 

 A term applied, in Botany, to leaves 

 which have three lance-shaped lobes, 

 one in the direction of the midrib, the 

 other two at the base, at right angles to 

 the first, as in arum maculatum. 



HASTINGS SAND. The middle 

 group of the Wealden formation, consti- j 

 160 



tuting the uppermost part of the Oolitic 

 system in England, and occurring around 

 Hastings in Sussex. It consists of yel- 

 lowish grains of sand, very loosely cohe- 

 rent, alternating with beds of clay and 

 conglomerate, containing fragments of 

 bones and scales of fishes. 



HA'TCHETINE. Mineral adipocire. 

 A wax-like substance occurring in the 

 nodules of iron-stone in South Wales, 

 and named after Mr. Hatchett. 



HAUSMA'NNITE. A designation of 

 pyramidal manganese ore. 



HAUSTELLA'TA {haustellium, a pro- 

 boscis). Haustellate insects ; a group in 

 which the mouth is furnished with a 

 haustellium, or proboscis, adapted for 

 suction. This division includes the 

 homopterous, heteropterous, lepidopte- 

 rous, and dipterous insects. See Mandi- 

 bulata. 



HAUYNE. Latialite. A blue mine- 

 ral, occurring in basalt or lava, and 

 named from the mineralogist Haiiy. 



HAY'TORITE. A variety of rhom- 

 boidal quartz, containing 0'5 per cent, of 

 oxide of iron. 



HEADLAND. Any projection of the 

 land into the sea. Thus, a cape is a 

 headland, and is distinguished in each 

 case by a particular designation ; a pro- 

 montory is also a headland, but, in ac- 

 cordance with its Latin derivation, is 

 applied only when the projecting head is 

 a high point or a rock. 



HEART-WHEEL. A mechanical con- 

 trivance employed in cotton mills for 

 converting a circular into an alternating 

 rectilinear motion. It consists of a re- 

 volving ellipse, on the edge of which a 

 moveable point or circle presses ; the 

 latter receives an alternating motion 

 from the circumference of the ellipse, 

 which in its revolution presses it to dif- 

 ferent distances from the centre of mo- 

 tion. 



HEART-WOOD. The popular name 

 for the hard interior portion of the stem 

 and branches of exogenous trees, as dis- 

 tinguished from sap-wood, or the exterior 

 and softer portion. In botany the former 

 is termed duramen, the latter alburnum. 



H EAT. In popular language, the sen- 

 sation experienced on touching a body of 

 a higher temperature than that of the 

 blood. In chemical language, it is the 

 cause of that sensation, or caloric, a term 

 by which philosophers distinguish the 

 matter of heat from its effect. 



HEAVY SPAR. Another name for 

 baryta, the heaviest of all the earths. 



