ART OF BUILDING. 245 



When the soil is loose to any great depth, the founda- 

 tion may be well established by turning inverted arches 

 under each aperture and opening, as the doors and 

 windows ; by this means the foundation is rendered per- 

 fectly safe and solid, because the sinking of the piers will 

 carry the arches with them, and thus push the ground 

 under them, which presses it against the under sides of 

 the arches ; the arches of course, will not give, it' pro- 

 perly constructed : where this expedient is noUised, those 

 parts of the wall which are under the apertures, or doors 

 and windows, not being so heavy as the solid parts of the 

 wall, will be left behind when the solid parts scttk-, be- 

 cause the resistance of the soil will keep them up, causing 

 fractures in the wall, and frequently in the window caps 

 and sills. 



In so essential part of a foundation as the arch, great 

 care should be paid to its curve, and the curve, called a 

 parabola, should be used in preference to any other ; next 

 to this the semi-circle. 



The most common method in this country is to estab- 

 lish foundations in soft earth, upon piles ; these arc driven 

 into the ground, and the foundation stones laid upon 

 them. In using piles, great care is requisite that 

 they be driven down to the firm bottom ; it some- 

 times happens that the piles stop before they have 

 reached the solid ground, and if the masonry is placed 

 upon them in that state, the Avails will certainly be rup- 

 tured therefore, such piles should be left a short time 

 at rest, and then apply the pile engine and it will drive 

 them down to the firm bottom : this stoppage i? pro- 

 duced by the friction of the pile and the resistance of 

 earth. An important instance of the fracture of walls 

 established upon piles occurred in Boston a few years 

 since on Central wharf. 



It sometimes occurs that a foundation is required to 

 be constructed on inclined ground, in which case the 

 walls should rise in a series of level steps. This will 

 endure a level and firm bed for the building walls, and 

 prevent their sliding, which they would be apt to <;> in 

 moist situations, thereby causing serious fractures if not 

 the entire destruction of the building. 



VOL. i. NO. x. '1- 



