572 



DETAILS OF CONSTRUCTION. 



those built of bricks, with good mortar, 

 because they attain a degree of homoge- 

 neousness which no construction of mor- 

 tar and stone has ever yet equalled. The 

 proof of this is found in the ancient brick 

 buildings of Italy. The walls next in 

 durability are those formed of fragments 

 of porous stone, compactly bedded in 

 good mortar or cement," as exhibited in 

 the oldest stone buildings we have in 

 Scotland, " and in that of the old Roman 

 castles throughout Britain and Germany. 

 The third in order are those (commonly 

 reckoned the first) which are composed 

 of very large blocks of squared stones, 

 and the strength of which does not at all 

 depend on mortar or cements of any 

 kind." — Cott., Farm, and Villa Arch. Of 

 this an excellent example may be seen on 

 entering Lincoln by the northern road. 



Stone, in general, is the first part of out- 

 buildings to decay. Care, therefore, should 

 be taken in its selection. On this subject 

 Brand has laid down the following rule : 

 " Boil two 1-inch cubes of the stone to 

 be tried in a solution of sulphate of soda, 

 saturated at a common temperature, for 

 half an hour ; then expose the cubes to 

 the air for evaporation ; the salt crys- 

 tallises, and has the effect of freezing on 

 the stone ; then dip the stone in the cold 

 solution until the crystals fall; after 

 this expose the stones to the air. This 

 experiment, repeated during five days, 

 will produce the same effect on the stone 

 which exposure in the open air would do 

 in many years." 



In stone building, the stones should be 

 invariably set on their natural bed, so 

 that they may lie in a position precisely 

 similar to that which they occupied in 

 the quarry. This caution specially needs 

 to be observed in the case of sandstone, 

 which is of comparatively modern forma- 

 tion, and is not of such intensity as gra- 

 nites and mountain limestone, and is 

 more easily acted upon in the direction of 

 its bed by the weather. Micaceous slate- 

 stones require the same precaution, and 

 are, from their want of solidity, and 

 their abounding in fissures, the worst 

 sort of stone that can be employed, as 

 they admit readily the rain-water to pass 

 through between the various laminae of 

 which they are composed. 



Of Slates, the best are from North 

 Wales, and are of fine texture and blue 



colour. The next are the Westmoreland, 

 of a light green colour, harmonising well 

 with buildings surrounded by trees. The 

 Devon and Cornwall slates are much in- 

 ferior as to durability. Their colour, 

 however, is good, being that of a purple 

 grey. The Dennybole quarry, in Corn- 

 wall, produces the largest, finest, and most 

 durable of the south-western formation. 

 Those of Eisdale arid Ballahulish are the 

 best in Scotland — very durable, but very 

 heavy. The thin drab-stone of Dorset- 

 shire, the Kentish rag-stone, and the red 

 and grey slate-stone of various parts of 

 Scotland, make picturesque roofs, but load 

 the roofs by far too much. The light- 

 blue Welsh slate is much less penetrable 

 by water than the dark blue sorts. Good 

 slates will not imbibe above iio of their 

 weight of water. Indeed, their wetting- 

 is merely superficial, and in summer they 

 will dry in half an hour. The Valentia 

 slates, from Ireland, are of excellent qua- 

 lity, and may be had of any reasonable 

 size or thickness. 



Tiles, whether plain or pan-tiles, con- 

 stitute a very heavy roofing. They tend 

 to render a house damp, from the quan- 

 tity of moisture they absorb. All un- 

 glazed tiles imbibe one-seventh part of 

 their weight of water in the space of ten 

 minutes, and cannot be deprived of this 

 water without a degree of heat equal to 

 60°, continued for six days. The red 

 coloured tiles in common use are ex- 

 tremely objectionable as a roofing for 

 ornamental buildings ; while tiles of other 

 forms and colours produce some of the 

 most beautiful of all roofs. Of these the 

 Grecian, Italian, Moorish, mathematical, 

 and new French, may be specially noticed. 

 These are either made of fire-clay, burn- 

 ing them to a soft stone colour, or are 

 coloured of various tints to harmonise 

 with the objects which surround them. 



Cramps are often used in tying together 

 the copings of walls, pits, &c. When 

 wrought iron is used, it should be dipped 

 in boiling oil and red lead, boiling pitch, or 

 be embedded in cement (not lime-mortar) 

 as a means to prevent oxidation. Copper 

 cramps are preferable, but are expensive ; 

 and cast-iron dove-tailed cramps are the 

 next best, particularly if tinned, or coated 

 by any of the preparations recently in- 

 vented for the preservation of metals.— 

 ( Vide Hothouse-building, &c.) 



