ART OF BUILDING. 241 



than thin mortar, and is generally poured upon masonry 

 to fill up all the interstices. 



Grubbstone mortar is made of water, lime, sand, and 

 small rough fragments of stone ; it is used for founda- 

 tions and other works in water ; it is sometimes employed 

 for filling up between the two faces of a wall, to render 

 it water tight. 



Having detailed in a brief manner the different mate- 

 rials used by the masons, we now proceed to show their 

 application. 



Masonry is the art of forming cut stone, rubble or 

 brick into masses by means of mortar or plaster ; of 

 course, there are several kinds of masonry the two 

 principal however, are Regular and Irregular. 



Regular masonry is formed of stones or bricks of a 

 regular form. The object of all kinds of masonry is to 

 form with a number of pieces of stone or brick, one mass 

 which shall have the eolidity of a single block. 



The ancients employed stones of a much greater size 

 than are used at the present time. In the ruins of Per- 

 sepolis there are single blocks, weighing over 500 tons. 

 In the great temple of Balbec, there are single blocks 

 weighing 1000 tons. 



In this country cut stones are called ashlar, of which 

 most of our stone edifices are built, the stones being 

 of various length, but should always be of the same length 

 for the same building. Where the face stones are not so 

 thick as the wall, it is customary to fill in the back with 

 rough materials, in which case the backs of the face 

 stone, or ashlar, should not be parallel to the front face, 

 but inclined ; and every stone should have its back inclin- 

 ed in the same direction, which will give a certain lap to 

 each course. In all kinds of face stone work, every 

 course should have a number of thorough stones in it, 

 that is, stones which go through the wall ; these are ne- 

 cessary to the stability of the work. 



Brick masonry is that which is most common in our 

 country. In building brick work in dry weather the 

 best of mortar is necessary, and the bricks should be 

 dipped in water as they are laid, to cause them to adhere ; 



