194 



Economical Mode of building 



common ones, and the rabbet, like that of a sash, would 

 prevent water from flowing through. A 4-inch wall, built in 

 this way, with posts at every four feet, would be as stiff and 

 strong as an ordinary 14-inch wall, and, excluding the original 



expense of brickmaking and 

 foundery apparatus, would 

 not cost above one third the 

 expense. The bottom course 

 of bricks should be laid 

 across, under the surface, as 

 in^^. 44., to form a broad 

 foundation. The general 

 appearance of such a wall 

 would be as vnjig. 45. Win- 

 dows might obviously be made, with perfect facility, of any 



required size, and 

 45 cast-iron frames and 



sashes are the cheap- 

 est of all kinds. 

 Mr. Frost's ingenious 





earthen tubes might 

 be used for filling the 

 interspaces of these 

 walls. When slates, 

 boards, or flags are 

 used, the breadth of 

 the rabbet in the iron post may be considerably less, say an 

 inch, as '\njig. 46. Slate houses of great strength and dura- 

 bility might be made by filling up the spaces with two 

 surfaces of slate, distant three or four inches, and 

 filling up the interval with gravel and grout, or 

 rammed puddle, as \\^fg. 4?., in which a is the iron 

 upright, b the slates, and c the puddle or filling-up 

 ^ matter. Slates thus placed, from the inertia and in- 

 elasticity of the mass, would almost resist fracture; a blow 



46 



