COTTAGE DWELLINGS IN VARIOUS STYLES. 189 these walls is, that they admit of being equally heated throughout, by a tube of hot water or steam conducted along the interior, just above the surface of the ground. Several cottages have been built with walls of this description, on the estate of Robert Donald, Esq., near Woking, Surrey. It is evident that brick walls on the same plan miglit be built of eighteen inches or two feet in width, or, indeed, of any width, by joining two nine-inch hollow walls together, as in fig. 331, which, if a garden wall, might be heated 331 Ml I i i I i M : I i : - I ; ; ! i — H— — ^^— — ^" , i , Mil r^ r:T I ,,_4-
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-^ — I — j — f— ^ — I — — — — -,— j — — ^H — - I __ J I I I I ; I I _ 1 ' I '. : 1 L_J L_J LJ_ on one side, without being heated on the other ; by carrying up the heading courses solid from the bottom, as in fig. 332 ; or, better, with a brick on edge wall in the centre, as in 332 fig. 333. A wall of this construction, with the bricks flat, would form one of the very cheapest and best descriptions of walls for a fruit-garden. For a fourteen-inch wall 333 bricks might be made of that length, as proposed by Dearn ; and, for a wall two feet or more in thickness, the interior might be entirely hollow, with cross walls every four or five feet, as shown in Gard. Mag., vol. iv. p. 228. To save bricks in the cross walls, and also to admit of the free transmission of heat from one division to another, they might be built in what is called the pigeon hole manner, viz. each stretching course having alternate vacancies, by leaving out every other brick, as in fig. 334. 334
