205 



The figures of the table on the preceding page are summarised below, 

 and the results are also presented in diagrammatic form in order to facili- 

 tate comparison with the other Colonial soils similarly examined. 



Pebbles Gravel Sand Silt Clay 



No. > 3 mm. 3 Inirn. 1 ; 05 mm. -05 -005 mm. < '005 mm. 



33 9-86 4-79 21 "37 48'63 15-35 



33a 5-27 5-17 18'59 45 "35 25 -62 



33b 7-65 4-25 19 '22 45-36 23-52 



It will be found of interest to compare these results with the figures 

 quoted from Snyder (see page 190) as the most satisfactory for wheat 

 production. As before observed, it do'es not by any means follow that 

 the optima of mechanical composition for wheat soils in the United States 

 of America are also the optima in the Cape Colony ; in fact, it would be 

 strange if such were the case, in view of the widely different climatic con- 

 ditions. 



By way of supplementing the diagrams which illustrate what I have 

 termed the " texture curves " of some of the soils examined, a photograph 

 is appended showing the actual proportions of the several grades of soil 

 particles separated by the above described processes from the former of the 

 above two soils, and from No. 24 of the Robertson soils.* It will be in- 

 teresting to compare this photograph with the diagrams drawn from the 

 calculated results of the mechanical analyses of the respective soils. 



CONCLUDING OBSERVATIONS. 



In bringing this record to a conclusion, the writer must express hia 

 sense of its incompleteness. True, no investigations of this nature can 

 ever bear the impress of finality, they must perforce continue incomplete 

 as long as agricultural chemistry has room to progress. But the incom- 

 pleteness that attaches to this special record is the inseparable adjunct of 

 contingencies which have all along restricted to one pair of hands at a 

 time the work of investigating the chemical problems of the soil in a 

 country so vast and varied, and possessing such diversities of temperature, 

 rainfall, and geological conditions, as this Colony presents. When, above 

 all, this investigation had to be sandwiched in amongst multifarious other 

 calls on time and attention or passed on to assistants, when time failed 

 entirely, as it did almost at the very outset, and the work had then to 

 be fitted in amongst their other duties the difficulties were greatly in- 

 creased ; and moreover, as no other researches of like nature were being 

 carried on within a radius of many thousand miles, special appliances 

 had to be procured from abroad, and perhaps tested for a considerable 

 time ere their unfitness stood revealed. Thus much time was continually 

 being lost, and great periodic gaps occurred in the pursuance of the work. 



There are also comparably great gaps of totally uninvestigated tracts of 

 country, and even the areas that were visited have been practically 

 skimmed over. Thus it has come about that much had to be done by 

 delegation, through written instructions a course which always fails to 

 secure uniformity for instance, in regard to collection of samples. Fre- 

 quently failure to carry out these instructions to the letter has either 



* It is in each case the surface layer of soil that is represented in the photograph. 



