FLOW OF WATER THROUGH PIPES. 143 



This table means that the size of tile given should 

 not be laid on a less grade nor in lines of greater 

 length, when laid upon that grade, than is given oppo- 

 site the size. If the formula should call for a certain 

 size when the length is greater than this, then use a 

 larger size than that denoted by the formula. 



