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angles to the back : this is done with a view to continue thelength of the board when too short. The heading-joints ingood work are always ploughed and tongued, as in flooring,dado, &e. In dado, the heading-joints, besides being ploughedand tongued, are also glued.
Head-Way of a Stair , the clear distance, measured per-pendicular to the horizon, from the tread of any step, resting-place, or landing, to the ceiling immediately above, in onerevolution, making allowance for the thickness of the steps.
HEARSE or Herse, a metal frame sometimes set overeffigies on tombs.
HEART-BOND, in masonry, the lapping of one stoneover two others, which together make the breadth of the wall.This is practised when thorough-stones cannot be procured.See Masonry.
HEATHER-ROOF, that kind of roof employed in build-ing which is thatched over or covered with heather or heath,instead of some other material. It is recommended, as welladapted to buildings of the farm description, by the writerof the Survey of the County of Argyle, in Scotland , on theprinciple that it does well with timber of the ordinary sort, iscapable of being procured for a trifle, lasts nearly as long asslates, and gives less trouble in the repair. It is asserted thata roof of this material, when well put on, will last onehundred years, provided the timber continues good that lengthof time. And it is stated, that formerly, most of the churchesin the above county were covered with this sort of roof;likewise, that heather-roofs are frequently met with in thedistrict of Cowal, and that there are a few of them inKin tyre.
This sort of material may certainly be employed withadvantage as a covering for small houses and other buildings,where other kinds of substances cannot be procured, except ata great expense ; but at the same time it is very inferior toslate, and other similar matters, in forming the coverings ofsuch erections.
HECATOMPEDON (from Iraror, a hundred, and waga fool ) a name given to the Parthenon , or temple of Minerva,at Athens .
HECATONSTYLON (Aaror-uXor) in ancient archi-tecture, a portico with a hundred columns. This name waspeculiar to the great portico of Pompey’s theatre, at Rome .
HECK, a rack.
HEEL, in mouldings, the same as the sima-inversa.
Heei. of a Rafter, the foot of the rafter, as it is formedto rest upon the wall-plate.
HEIGHT, the perpendicular distance of the most remotepart of a body from the plane on which it rests.
HELICOID PARABOLA, or the Parabolic Spiral,a curve arising upon a supposition of the axis of the commonApollonian parabola being bent round into the periphery of acircle. The helicoid parabola, therefore, is a line passingthrough the extremities of the ordinates, which convergetowards the centre of the said circle.
HELIOPOLIS , or The City of the Sun, in ancientgeography, a city of Egypt , placed by geographers not farfrom Helle, at some distance from the eastern point of theDelta. It was built, according to Strabo , on a long artificialmount of earth, so as to be out of the reach of the inundation.This causeway, covered with rubbish, is still visible twoleagues to the north-east of Grand Cairo, and three from theseparation of the Nile . This city had a temple to the sun,where a particular place was set apart for the feeding of thesacred ox, which was there adored under the name Mnevis, ashe was at Memphis under that of Apis. There was also inthis city another magnificent temple, in the ancient Egyptian
taste, with avenues of sphinxes and superb obelisks, before theprincipal entry. These temples were fallen into decay underthe reign of Augustus ; as the city had been laid waste withfire and sword by the fury of Cambyses . Of the four obeliskbuilt by Socliis in that town, two were removed to Rom e >another has been destroyed by the Arabs ; and the last o»them is still standing on its pedestal. It is composed of ablock of Thebaic stone, perfectly polished, and is, withoutincluding its base, 68 feet high, and about 6^ feet wide on eacnaspect. It is covered with hieroglyphics. This beautuU*monument, and a sphinx of yellowish marble, overset in themud, are the only remains of Heliopolis . See EgyptianArchitecture.
HELIX, a term applied to the little scrolls in the Corinthiancapital, called also urilla : they are sixteen in number, viz-two at every angle, and two in the middle of the abacus>branching out of the caulicoli or stalks which rise betweenthe leaves.
HELMET , a warlike ornament, in imitation of the helm eworn by the cavaliers, both in war and in tournaments, as acover and defence of the head ; the helmet is known by diver 3other names, as the head-piece, steel-cap, &c. The German 3call it helen or hellem ; the Italians elmo ; the French casq ue >as did also the ancient English .
The helmet covered the head and face, only leaving nIaperture about the eyes, secured by bars, which served a3a visor. ,
HEM, the protuberant part of the Ionic capital, formeby spirals.
HEMI, a word used in the composition of divers term 3 'It signifies the same with semi or demi, viz., half; being atlabbreviation of liparvg, hemisys, which signifies the saffl e ‘The Greeks retrenched the last syllable of the wordin the composition of words ; and, after their example, we haN®done so too, in most of the compounds borrowed from them-
HEMICYCLE, (Latin, hemicyclium , compounded ®^l/piirvg, half, and kvkXoq, circle') a semicircle. Thisparticularly applied, in architecture, to vaults in the era®form ; and arches, or sweeps of vaults, constituting a per‘®
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semicircle. To construct an arch of hewn stone, they di, the hemioycle into so many voussoirs; taking care to mthem an uneven number, that there be no joint in the mid® ’where the key-stone should be. .
HEMICYCLIUM, a part of the orchestra in the ancte»*theatre. Scaliger , however, observes, it was no standing P fllof the orchestra ; being only used in dramatic pieces, wh®some person was supposed to be arrived from sea, asPlautius’s Rudens . c
HEMISPHERE, (Latin , hemispherium, compounded^hpiavg, half, and otjiaipa, sphere) in geometiy, one half 0globe, or sphere, when divided into two by a plane pa 331 6through its centre. „
HEMISPHEROIDAL, a body approaching to the ^S u ^ eof a hemisphere, but not exactly so; of this descriptionwhat may be termed elliptical domes, upon either axis-HEMITRIGLYPH, the half triglyph.
HENDECAGON, Endecagon, or Undecagon, (®° 9pounded of ivStica, eleven, and yon ia, angle) in geometry,’figure which has eleven sides, and as many angles. If each s'^of this figure be 1, its area will be equal to 9.3656399 —■ *tangent 73pj, radius being 1. >a
HEPTAGON, (of ivTa, septem, seven, and y tovia, aP ^, eliin geometry, a figure consisting of seven sides and s ® ^angles. If the sides and angles be all equal, it i 3 ca j 3a regular heptagon. The area of a regular heptagonequal to the square of one of its sides multiph®®3.6339126.