SECTION 22. OBSERVATION. 297 



tion of the blood, whilst astronomers refer to the plane pre- 

 sented by the sea rather than to the uneven land when they 

 desire to show the globular character of the earth, or call to 

 witness the polar star to prove that the earth's axis does not 

 suffer any material change with time. Physical geographers 

 thus colour the map of the world to indicate now geological 

 formations, now altitudes or temperatures, now barometric pres- 

 sure or rainfall, now winds or ocean currents, and now the 

 earth's Vegetation, and anatomists present us in their atlases 

 with a man now all muscles, now all circulatory organs, now 

 all skeleton, and so on. In arithmetic the unitary method offers 

 an illustration, as also the general formulae in mathematics 

 and the decimal system of measurement, 1 model experiments 

 where one factor at a time is tested, especially an experimentum 

 crucis, exemplify this Conclusion; and the simplest case includes 

 mathematical or some other rigidly definite form of statement, 

 and choosing for recollection, for study, for illustration, or for 

 constructive purposes, a single typical example in connection 

 with classes of facts. Thus, in comparing races, we may compare 

 the European with the Australian bushman, as races culturally 

 placed at the opposite sides of the scale, and in comparing 

 their respective capacities we may examine their scholastic 

 achievements under fairly identical circumstances, whilst in 

 comparing individuals we may contrast an average person in 

 intellect and moral attainments with a man of first-class scien- 

 tific or moral standing. Darwin was well aware of the advantage 

 of this Conclusion : "As soon as the idea of descent of species 

 took definite shape in [Darwin's] mind, he determined, after 

 deliberation, to take up the study of domestic pigeons. H& 

 selected these because the variations were more numerous and 

 plainer, more of them had arisen in the historical period than 

 is usual with animal groups, the material was abundant and 

 easily accessible, etc." (Frank Cramer, op. cit, p. 53.) 2 



1 The English system of measurement and spelling and the Roman 

 numerals are painf'ul revelations of the opposite method. Compare also 

 the French naming of some figures: 99 = quatre-vingt-dix-neuf. 



2 "In settling valencies, the greatest caution has accordingly to be observed 

 by the chemist. He deals, if possible, especially in studying the elements 

 with higher valencies, only with compounds of simple type containing if 

 possible only one atom in the molecule of the polyvalent element, and he 

 directs his attention to the compound which he can prepare with the 

 highest valency exhibited, and in that compound univalent elements so far 

 as possible occupying the available dynamic centres of the polyvalent 

 element." (Benjamin Moore, op. cit., pp. 91-92.) 



"Long ago, physiologists learned that the quest for explanations of living 

 activities lay along the line of investigating them in their most rudimentary 

 expression." (W. A. Locy, op. cit., p. 104.) 



The Report of the Indian Factory Labour Commission tells how "one 

 witness of long practical experience stated that any man would feel exhausted 

 if he merely sat in a chair in some of the workrooms for eight or nine 

 hours, the atmosphere was so foul". Given a regular succession of move- 



