74 WAVES OF SAND AND SNOW 



the mechanical analysis which I made of the 

 sample. In order to make the analysis I had six 

 sieves of copper-gauze made with square meshes 

 from rW to ttIx of an inch in diameter. I 



passed the sand through one sieve after the other, 

 with prolonged tappings, and weighed the 

 separated portions. Twenty grams weight of the 

 material were taken and 19-981 grams were re- 

 covered, the difference of 0019 gram remaining 

 attached to the sieves or being otherwise lost. The 

 result was as follows : — 



Sand-grains more than -^^ inch diameter 

 Less than yV inch but greater than 2V i^^ch 



1 

 1 

 1 



T"8^ 



4~S 11 



1 9 a 1) 



1 



TF4 1) 



Less than 



Weight. Percentage 



O'OOO 0"000 



o'oo3 0*015 



0"4I2 2'o6o 



18775 93*875 



0790 3-950 



G-QOI 0-005 



O'COO 0*000 



Thus, in round numbers, 2 per cent, by weight 

 of the sand -grains had a diameter more than 4^ of 

 an inch and 4 per cent, diameter less than yV- Of 

 the remaining 94 per cent., the largest grain was 

 not more than twice the diameter of the smallest. 



