192 OF THE PRESSURE OF FLUIDS ON DYKES AND EMBANKM EN TS. 



Put b zz: DC, the breadth of the section's base, or the thickness of the 

 dyke at the foundation, 



D zz AK or BL, the perpendicular altitude or height of the 

 section, 



d =z EF, the perpendicular depth of the fluid whose surface is 

 at EM, 



I zz: DF, the distance between the near extremity of the base at 

 D, and the perpendicular E F, 



c zz: DK, the measure of the slope AD, or the distance between 

 the near extremity of the base at D, and the perpendi- 

 cular from the extremity of the opposite side at A, 



c zz: CL, the distance between the remote extremity of the base 

 at c, and the perpendicular from the extremity of the 

 opposite side at B, or the measure of the slope BC, 



a zz: ABCD, the area of a vertical section of the obstacle to be 

 displaced, 



p the horizontal pressure of the fluid on the increment of EG, 



/ zz: the force with which the horizontal pressure operates to 

 overcome the resistance of the dyke, 



m zz: the momentum of that force, 



p' = the vertical pressure of the fluid on the increment of EG, 



/' zr the force with which the vertical pressure resists the dis- 

 placement of the obstacle, 



tfi'nr the momentum of that force, 



w zz: the symbol which denotes the weight of the dyke or obstacle 

 of resistance, 



F =z the force with which it opposes the horizontal pressure of 

 the fluid, 



M zz the momentum of that force, 



s zz- the specific gravity of the fluid, 



s' zz: the specific gravity of the dyke, or opposing body, 



z zz: EG, any small portion of the sloping side AD on which the 

 fluid presses, 



z zz: the increment or fluxion of that portion, 



y zz: EH, the perpendicular depth of the point G, 



y z= the increment or fluxion of y, 



x zz: G H, the ordinate or horizontal distance, 



and x z= the increment or fluxion of the horizontal ordinate or dis- 

 tance G H. 



Then, since the pressure upon any line or surface, is equal to, or 

 expressed by the magnitude of that line or surface, multiplied by the 



