lo- 3 



168 Clas,siJicatioH of Soils 



summatiou percentage against either an arbitrary scale, a natural scale 

 of mean diameters (7), or more conveniently tlir logarithms of the mean 

 diameters, is to be preferred. By this means a very complete representa- 

 tion of the analysis can be made, and the gradual gradation from type 

 to type clearly seen. 1ml t he method becomes unintelligible if any number 

 of soils are plotted on one diagram. A number of soil types arc shown in 

 Fig. 1 , where the summation percentages are plotted against the logarithms 



Limit oi" EngmshFinrEarth 



lo.'OOOl ■ 



IWfil 



U.S. Eai'ly Market Garden 



Market Garden 



U.S. Market Garden 



Sheep and liarley 



Cherries and Fine Hops 



Tobacco 



Potato 



.. Orcliards 



•— .■ — «- Coarse Hops 



• • • • TT.S. Wheat 



. ■ >. Wheat 



l'..S. Wheat and Grass 



U.S tira=s and Wh^at 



Fig. 1. Comparison of types liy enmniation i\irvcs. 



of the mean diameters of the groups, the points so obtained being joined 

 up by a smooth curve. The value -0001 mm. has been taken as the lower 

 hraiting value of the dimensions of the clay group. This is purely an 

 arbitrary proceeding. The proportion of "colloid" clay could here be 



