TIL

489

Tim

Throat. See Gorge, and Gula.

-THROATING, the channel cut on the underside of aj 0tle ) &c., to prevent the further passage of rain, which isY collected, and drips off the building.

„-THROUGH-STONE, a bond stone; one which runs^Ugh the heart of the work.

c , *IE, (from the Saxon, tian, to bind,) a timber, strin^a ain , or iron rod, connecting two bodies together which havee ndency to diverge from each other. The tie-beams, dia® ties, and truss-posts, are ties. Braces may act either(■ tle s or straining-pieces : straining-pieces are preferable to8 > for these cannot be so well secured at the joints asfining-pieces.

^-Ue-Beam, the beam which connects the bottom of a pairPrincipal rafters, and prevents them from bursting out theSee Tie and Truss.

Tie-Rod. See Tension-Rod.

^ TIERCE POINT, the vertex of an equilateral triangle.^ rc hes, or vaults, of the third point, which the Italians callitit terzo Qcuto, are such as consist of two arcs of a circleersecting at the top.

GGE, a term used by the French for the shaft of a column.

. iLE, (from the Saxon, tigle,) an artificial stone, or broadCo" 1 krick, made of dried earth, and burnt in a kiln, used infring buildings. See Brick .

-lues have various names, according to their surface, shape,situation.

j Pilose of a rectangular form, with a plane surface, are^nominated plane tiles and crown tiles: their dimensionsa bout 101 inches long, 6 inches broad, and five-eighthsinch thick. A plane tile weighs from 21b. to 2£lb.

^ those of a cylindric form are denominated ridge tiles, roofL 1 °r hip tiles, and are used in covering the ridges ofin U * es - Their dimensions are, in length, about 12 inches,^“teadth 10, and in thickness five-eighths of an inch.Wa" ' Ve 'ght of a ridge tile is about 41 lb. Tiles which are<M | ee(1 on the angle formed by the two sloping sides, arehip tiles.

*ita • t0 k e placed in gutters, have a form adapted to theira. : the weight of a gutter tile is the same as that of

tY tile -

* les °1 a rectangular outline, with a surface both concaveWt C ° nvex > are denominated pan tiles ; these have no holes,C.Y hung on the lath, by means of a ledge, formed ini tl J r making, at their upper ends : they are usually 141-„ ea long, and 10 broad. They weigh from 51b. to 5^ lb.

iihYe-Creasing, tw0 rows °T t'les placedii) C | i er the coping of a wall, andtL 68 from the surface, for dischargini[ efr om.

Coi lLEs . Encaustic, decorative tiles formed of different-t’l le tCf l clays, arranged so as to form a variety of patterns,htt '’ r ° Un| l is usually red, and this being stamped with someff eQ ern > the recess is filled in with clay of various colours,4 y ,® ntl y white, the whole being afterwards glazed over with^tt„ lo ' v glaze. Frequently each tile presents a completeV Y hut at other times a pattern is composed of four orVd hi 03 arranged in juxtaposition. Such tiles are mostlyW* ecclesiastical buildings, and are often interspersed inor der amongst tiles of a plainer description, by which■Pit Ihelr beauties are more fully displayed.

\ vl^G, the act of laying tiles for the covering of a build-.’ c h ma y he done either with plane tiles or pan tiles.a 6 ’ s preferable to pan tiling. Plane tiles are laidli ' Inc h g au g e > with or without mortar ; and pan tiles atH ea °r 1inch gauge, though some use a gauge of 12y Q ’ hut this distance is too great.

'O- n. 6 i

horizontallyprojecting about threethe rain-water

From the frequent repairing of tiled roofs, and their fieryappearance, slating has now become the general covering,and tiling is seldom used except for common cottages, sheds,and out-houses, as being more expensive to keep in repairthan slating.

TIMBER, (from the Saxon, timhrian, to build,) in car-pentry, a piece of wood for supporting some part or parts ofthe building, or to give strength to any part thereof.

Timbers, in a building, support parts of the fabric inthree different ways, viz., by lateral strain, by tension, andby compression.

Timber, wood felled and seasoned for the purpose ofbuilding. Many kinds of woods are useful for building pur-poses, but those most frequently employed are oak, fir, andpine; but before entering into the peculiar properties ofthese, it will be as well to give some idea of the structureand growth of trees in general.

Upon observing the transverse section of the stem or trunkof a tree, the wood will be found to be composed of numer-ous concentric layers or rings, which are more or less definedin different trees. Where the rings are well defined, theywill be found to consist of two parts, the outer being hard,compact, and of a dark colour, while the inner is of a lightertint, more soft and porous. In the centre of the tree is thepith, and on the exterior the bark, and it will be observed,that the concentric rings become more soft, and contain moresap as they recede from the pith, the more compact layersnearest the pith being termed heart-wood.

The structure of a tree appears to be composed of minutevessels for conveying nutriment from the roots ; the spacebetween these vessels being occupied by cells, which areengaged in performing the function of secretion. The vesselsin the growing tree convey the sap in a liquid state from theroots to the leaves, whence it descends in a less liquid statethrough the bark, and is at last deposited in an altered statebetween the bark and the last year’s wood, forming a newlayer of bark and sap-wood, the old bark being pushed out-ward, and the inner layers being compressed, probably in anequal degree. The sap begins to ascend in the spring of theyear, and flows principally through the annual rings nextthe bark, which contain most sap-wood. In its ascent, itwould appear to dissolve some part of a substance which hadaccumulated in the vessels during the preceding winter, forthe nourishment of the buds, leaves, and new wood ; and thisaccounts for the viscous state of the sap on its descent. Asthe leaves expand, the sap ceases to flow, and the bark againadheres to the wood, and, from the middle of June to themiddle of August, there appears to be a pause in vegetation ;but after this period, the sap again begins to flow.

As this process goes on from year to year, the fluid partsof the interior of the wood, are absorbed by the new woodand leaves, and the vessels through which they flow, beingpressed more closely together by the growth of new wood,become harder and harder, until at last the sap-wood is con-verted into heart-wood; for it would appear, that there isnothing of the character of solid fibres in wood, the morecompact parts being composed solely of the linings of thevessels and cells deprived of their moisture, and packedclosely together. 1 When trees arrive at this stage of exist-ence, that is to say, when the sap-wood has become heart-wood, and the greater part of the moisture has been expelled,they are in a fit state to be felled for the purposes of building.The best time for felling is in mid-winter or midsummer ;for in the former the sap has ceased to flow, and in thelatter it is expended in the production of leaves. Besidesthe concentric rings, another series of lines may be observedWith more or less facility in the sections of various trees ;