CHEAP AND DURABLE STRUCTtTRES. 221 



In a single day three courses may be laid, one over the One story may 

 other, so that a wall of eight or nine feet, or one story high, ^ 

 may be raised in one day. Experience has proved, that as 

 soon as raised to a proper height for flooring, the heaviest 

 beams and rafters may, without danger, be placed on the walls, 

 and that the thickest timber of a roof may be laid on the 

 gables the instant they are completed. 



On Earth proper for Pise. 



First, — All earths in general ar£ fit for that use, when they Buildings tnny 

 have not Ihe lightness of poor lands, nor the stiffness of clay. ^arth not too 



Secondly,— All earths fit for vegetation. I'ght ox too 



Thirdly,— Brick earths. 



Fourthly, — Strong earths, with a mixture of small gravel, 

 which for that reason cannot serve for making either bricks, 

 tiles, or pottery, but make the best pise. 



The following appearances indicate that the earth in which How to nhus^ 

 they are found is fit fox building. When a pick-axe, spade, or earth 

 plough brings up large lumps of earth at a time; when arable 

 iands lie in cjodsor lumps; when field-mice have made them- 

 selves subterraneous passages in the earth ; all these are favor- 

 able signs. Vv'hen the roads of a village, having been worn away 

 by the wjier CL^ntmually running over them, are lower than the 

 otiier lands, and the sides of those roads support themselves 

 almost u[>nght, it is a sure mark that the pise may be executed 

 in that village. 



Proper earth is found at the bottom of the slopes of low —and to im- 

 11^.. . ^ T 1 1 • I • prove it if re- 



ianus tnat are cultivated, because every year the ram brings quij-gj^ 



dowii the good earth, li is also found on the banks of rivers. 



If the earth to be had is not quite fit, it may be mixed to 



make it so. Strong earths must be tempered with light ; those 



in which clay predominates, with others composed more of 



chalk and sand ; and those of a rich substance with others of 



a poor nature. It will not be amiss to mix with the earth 



some small pebbles, gravel, rubbish of mortar, or any small 



mineral sub-tances ; but none of the animal or vegetable kind 



must be admitted. Such hard substances bind the earth The old walls 



' firmly between them ; so that a well worked earth, in which '^J^^^Q a- as a 



there is a mixture of gravel, becomes so hard at the end of 



two years that a chisel must be ^sed to break it, as if it were 



treestone. 



Expert' 



