STRAINS ON GATES. 



49 



If the sill is submerged, it is obvious that the above method will 

 only apply to the part of the gate above the surface level of the outer 

 water. The submerged portion is subject to uniform pressure, and 

 can readily be divided into any re- 

 quired number of equal parts. 



The proof of the above depends on 

 the fact that if A C (Fig. 365) be 

 any given finite line, and A D C a 

 semicircle described thereon, then if 

 A C is divided into any two parts at 

 m, and from m a line be drawn perpendicular to A C, cutting the 

 semicircle A D C in d, the point is such that joining A and d by 

 the straight line A d t 



AtP Am 

 A? = ~Ac 



FIG. 365. 



