348 ME. L. F. EICHAEDSON: APPEOXIMATE ARITHMETICAL SOLUTION 



was derived from the value of x' & t the nearest point on the masonry-water surface 



1 ' 

 by adding or subtracting the value of jA- at that point, multiplied by the distance to 



that point. The final body values of x' were arrived at by the process which has 

 been compared to hand-scraping in 3 - 3 above. They are justified by the very small 



1-70 >4-S 3-64- 5-17 



3-37 



values of ^ j'^' belonging to them. They are given to three places of decimals merely 

 in order to get smooth curves of stress. The interpolated boundary values may well 

 be +0 - 02 in error, so that the third decimal has no real significance. The stresses 

 deduced from this table are shown in two cases in figs. 8 and 9. It is seen that the 

 sharp oscillations revealed in the stress by the fine differences are passed over by the 

 coarse differences. The relation between the stresses near the front toe is, however, 

 not consistent with the proportionality of the error to h 2 . This indicates that the 

 assumptions which have been made as to boundary conditions have not been quite 

 consistent with one another.* Nevertheless, the scheme adopted with h = \ is to be 

 * Or that the term in h 4 in the error cannot be neglected. 



