C. I.. Whittles 179 



Application to the Preparation of Maps. 



If each, of the tliree primary colours be taken to represent one of the 

 three constituents (Coarse, Medium, and Fine), then to any position ou 

 the triangle is a corresponding definite colour, produced by a combina- 

 tion of the three primary colours in the same proportions. Any desired 

 degree of differentiation may be attained by using a sufficiently large 

 number of combinations. Steps of 5 per cent, would give 231 types, and 

 this would be sufficiently accurate for all purposes, as will be seen from 

 a consideration of Fig. 5. For the preparation of the drift maps of a 

 district, stejjs of 10 per cent, giving 66 types would probably be sufficient. 

 The proportion of stones and gravel, chalk, organic matter, etc., could 

 be shown by dots or shading. Maps of the soil and subsoil prepared on 

 these hnes would be of great value. 



In conclusion, the writer begs to tender his thanks to all those who 

 have suppUed him with data and other help. 



A Bibliography on Soil Classification, with data for soil types. 



(1) AsHBY. .S. F. ( 190.")). A Contribution to the study of Factor.s affecting tlie Quality and 



C'(jinposition of Potatoes. Jour. Aijric. Sci. 1, 350. 



(2) Atterbeku, a. (1908). On Metliods of clay analysis. A'. Luiullhr. Ahul. Hniull. ocli 



Tidsl-r. 47, Nos. 5-0. 



(3) (1909). The constituents of mineral .soils; the analysis, classitioation and 



prmcipal properties of clay soils. Comjit. Rend. Conf. Inicnml. Aijrog^ol. [Buda- 

 pest], 1. 



(4) (1912). Mechanical soil analysis and classification of iSvvedish mineral soils. 



A'. Landihr. Akad. Hand!, och Tidsh: 51, No. 0; Internat. Mill. Bodciik. 2, No. 4. 



(5) (1916). The classification of humus-free and huifius-poor mineral soils of 



Sweden according to their consistencies. Internat. Mitt. Bodenk. 6. 



(ij) Atteeberg, a. and Joiian.s,son (1916). The classification of the mineral soils of high 



humus content of Sweden. Internat. Mitt. Bodenk. 6. 

 (7) Baker, H. A. (1920). Investigation of the mechanical constitution of loose arenaceous 



sediments by tlie method of elutriation. Geological Magazine, 57, Nos. 7-9. 

 (S) BjjArlvkke, K. O. (1901-2). On the Classification of Soils. Berg. Norges. Laiidbr. 



Hoiskolen Virks, App. 

 (9) Chulnoky, E. von (1909). Soil type as determined by climatic zones. Compt. Rend. 



Conf. Internat. Agroge'ol. [Bndapcst], 1, l(i3-176. 



( 10) Coffey, G. N. ( 1916). The present status and future development of soil classification. 



Jour. Atner. Soc. Agron. 8, 239. 



(11) FiPPiN, E. 0. (1911). The practical classification of soils. Proc. Atner. iSoc. Agron. 3, 



70-89. 



(12) Foreman, F. W. (1907). Soils of Cambridgeshire. Jour. Agric. Sei. 2, No. 2, 161. 



(13) CJiMMiNGHAM, C. T. (1912). Annual Report of the National Frnil and Cider Institute. 



