STRAINS ON GATES. 



417 



the extremity of the water-bearing surface at the heel-post, a line to 

 e c be drawn perpendicular to A D, and cutting the centre-line of the 

 passage in c, then will the length of the line c e be proportioned to 

 the magnitude of tho reaction H, and the length of the line cf will 

 be proportional to tho magnitude of tho reaction M ; that is to say, 

 H = p x c e, and M = p X cf. Further, if g bo any point on the 



Nj 



i- I . 



\ \ I 



FIG. 363. 



back of the gate, the length of the line c g will be proportional to the 

 magnitude of the resultant force B, acting on any vertical section 

 passing through g ; that is to say, B = p X c g, and the direction of 

 such resultant will be perpendicular to eg. 



To find the position of the resultant force R acting on any vertical 

 section passing through g, let Fig. 363 be an enlarged plan of the 

 gate, A D and B D the lines of direction of H and M, C the point on 



2E 



