FOUNDATIONS. 



22 9 



direction of the pressure which they have to bear; and by 

 breaking joints avoid all long continuous joints parallel to 

 that pressure. 



II. Use the largest stones for the foundation course. 



III. Lay all stones which consist of layers in such manner 

 that the principal pressure which they may have to bear shall 

 act in a direction perpendicular, or as nearly as possible, to 

 the direction of the layers. This is called laying the stone on 

 its natural bed, and is of primary importance for strength and 

 durability. 



IV. Moisten the surface of dry and porous stones before 

 bedding them, in order that the mortar may not be dried too 

 fast and reduced to powder by the stone absorbing its mois- 

 ture. 



V. Fill all parts of every joint, and all spaces between the 

 stones, with mortar, taking care at the same time that such 

 spaces shall be as small as possible." 



From various authorities the following table has been 

 compiled : 



SAFE BEARING-VALUE OF MASONRY AND MODULUS OF RUPTURE OF 

 MATERIALS. 



Brick Masonry. There is no generally recognized manu- 

 facturers' standard brick, the general character and dimen- 

 sions varying considerably in different localities, but an average 

 size is 8y X 4" X 2J-" ; such brick, when dry, will weigh abou. 

 5 pounds each, and in rough reckoning 500 such brick arc 



