Walls 41 



The thinnest possible wall of brick is 

 four inches, one brick deep. (See Fig. 

 13.) This, if built straight, would have 

 little strength laterally and therefore a 

 four inch wall is run zig-zag like a snake 

 fence or broken up into short runs by 

 other methods. If each run is not too 

 long and the height is low, say not over 

 five feet, a fairly strong wall is construct- 

 ed. The serpentine fence at the Uni- 



The zigzag brick wall can be built one brick deep. 

 Less space is used if piers are placed at inter- 

 vals 



versity of Virginia, designed by Thomas 

 Jefferson, is an interesting example. 

 This zig-zagging however takes up ground 

 space so strength may be secured by us- 

 ing piers at 6 to 10 foot intervals. If 

 carried below the frost line greater safety 

 is the result, for a wall so thin has little 

 weight and is easily heaved out of place. 



Some walls are built with two thick- 

 nesses of brick and an air space between. 

 (See Fig. 14.) The two shells are held 



