of maximum slope , it baing precisely under these theoretical con- 

 ditions, of reduced joints, when the calculating procedure follow- 

 ed, based on internal pressures which must be transmitted through 

 those joints, lacks applicability. If the blocks move through 

 any cause or settlement, the cited three theoretical dimensions 

 no longer really exist, the coefficient Ri becoming the N determined 

 only on the basis of the overall dimension of the stone. 



Although only under the heading of curiosity, it is also inter- 

 esting to compare the results obtained for the theoretical value A 1 



» 2 ff r with the practical results pertaining to the limiting 



LK 

 velocities of erosion on the bottom of a canal, whose bed we 

 suppose horizontal, that is to say oc = o, and the formula that 

 gives us the weight of the individual stones would be: 



P = NA 3 d 

 (d - IP 



we get 



and since 



A' ; 27Tr 2 

 LK 



p = 8 rr 3 Nd 



(d - 1)3 



V pax = 7f r and T = /y LK 



T 



T V? 



one obtains 



P * SNdt/ max 



g 3 (d-l)3 



Applying this formula for the velocity in the canal, y max = 

 1 meter/second, and with a mean specific weight of material that 

 constitutes the individual stones or grains of d =2.6 metric tons/ 

 m^, one obtains: 



P - 8 x 15 x 2.6 x l 6 - 0.081 kilogram, 



9.81 3 x 1.63 

 cube of sidi 



i = 3 rr~ Jte« 



VlOOC d V 2 60( 



which represents a cube of side: 

 3/— r 3 



081 => 0.03 meter. 



23 



