STORAGE AND DISTRIBUTION. 



IIQ 



wards due to gravity which constitutes the resisting 

 moment. It then remains with the designer to make 

 the resisting moment greater than the overturning 

 moment. In the first place, let us investigate certain 

 formulae whereby the approximate thickness of a wall 

 can be found, because when this is found a rough 

 idea can be formed of the section of the wall which 

 must fulfil the above conditions. 



Let D = the depth of water to be retained in feet. 



Let W = the weight of i cub. ft. of the wall, as 

 per table. 



STRENGTH AND WEIGHT OF MATERIALS. 



Let w = 62'$ Ib. = weight of i cub. ft. of water. 

 Let T mean thickness of wall in feet. 



Then T = ';D tan - 



(30) 



The term tan - demands attention. This is a 



2 



quantity which is included in order to render the 

 formula applicable to cases of walls which retain 

 earth instead of water, and such cases will occur 



