68 



GARDEN WALLS. 



seventh of sand, and one-seventh of lime, 

 the whole being incorporated with a 

 sufficient quantity of water. 



As an illustration of the economy of 

 this kind of foundation, a rood of work 

 can be done in most localities for less 

 than £i — a price much below even that 

 generally charged for common rubble. — 

 (Vide Estimates and Prices.) 



§ 3. — MATERIALS FOE GARDEN WALLS. 



Of all materials, bricks are unquestion- 

 ably the best, as they are warmer and 

 more convenient for training trees upon 

 than any other. They are also, if the 

 bricks are well burned, equally durable, 

 if not more so, than stone, and admit 

 of being built hollow, for the purpose 

 of being heated either by hot-water 

 pipes, tanks, or smoke flues ; while, at 

 the same time, even when the duty 

 on bricks was considerable, walls of them 

 could be built cheaper than of common 

 rubble stone. Forsyth, in " Treatise on 

 Fruit Trees," (p. 325,) goes so far as to 

 say, "Where brick cannot be got, it is 

 better to dispense with walls altogether, 

 or to adopt wooden ones." Much as 

 we prefer brick walls, we must protest 

 against this opinion, as many excellent 

 walls have been built of stone, and 

 useful ones of various other materials. 



In England, garden walls are usually 

 of brick — that article being the common 

 building material : in Scotland, of brick, 

 and often of stone, as the latter is the 

 material natural to the country. Out of 

 Britain fine garden walls are not to be 

 found — for even the brick ones on the 

 Continent are very inferior, both in mate- 

 rial and workmanship, to our own. The 

 celebrated vine and peach walls at 

 Thomery, described in the " Pomona 

 Francaise," were long built of mud plas- 

 tered over; but, some years ago, stone 

 walls built with mud as a substitute for 

 lime mortar, and even stone walls laid 

 dry, after the manner of the " stone 

 dykes" for enclosing fields in Scotland, 

 were substituted in their place ; a circum- 

 stance which proves two facts— namely, 

 the greater wealth of Britain, and the 

 small importance attached to walls in 

 France, so far as the ripening of the fruit 

 is concerned. 



Hollow bricks are an improvementwhich 

 will be noticed elsewhere. They are one 

 of the advantages which have been de- 

 rived from the removal of the excise duty 

 on this material. They may now be 

 manufactured of any size, and, by the 

 addition of fire-clay, be made to resemble 

 stone ashlar. Composition bricks, formed 

 of common clay, fire-clay, and pounded 

 iron-stone, when thoroughly burned, are 

 the most durable of any; and, from their 

 close texture, they are incapable of ab- 

 sorbing more than a very small quantity 

 of water: hence, next to dark-coloured 

 whinstone, they are the most durable and 

 warmest of any. 



Dark-coloured whinstone (the green- 

 stone and basalt of mineralogists) is con- 

 sidered by Nicol the best material next 

 to brick. In the gardens of the Caledo- 

 nian Horticultural Society of Scotland 

 are specimens of stone walls of various 

 kinds. Of these, we believe the general 

 opinion is in favour of the dark whin- 

 stone, as it absorbs and retains heat more 

 than any other, by reason of its near ap- 

 proach to black, and of its close texture 

 or grain, causing it to repel moisture 

 better, or rather to retain it less, than 

 any other stone. 



Subsequent experiments in the same 

 garden led to the following results as re- 

 gards a sloping wall inclined to the hori- 

 zon at an angle of about 50°, a wall 

 coloured black, and a perpendicular wall, 

 and also as between perpendicular walls 

 of freestone, whinstone, and brick. The 

 sloping, the black, and the freestone walls 

 indicated the same temperature at six 

 o'clock in the evening ; the average of the 

 brick wall at that hour was a degree 

 lower during the month of April. This 

 wall, however, being more porous, and 

 retaining a greater quantity of heat, 

 showed during the month of May a con- 

 siderably higher temperature than any of 

 the others — owing, of course, to the in- 

 creased influence of the sun. We suspect, 

 however, another cause for this increase 

 of heat — namely, the month of May being 

 a dry month, less moisture was probably 

 absorbed than in the previous or after 

 months. The average temperature of the 

 sloping wall at one o'clock in the after- 

 noon was 7° higher than that of the brick 

 wall. The dark-coloured whinstone, (ba- 

 salt,) at the same hour, was only 3° lower 



