SECTION 13. GENERALISATION OR EXTENSION. 107 



teacher the ages of the children. The teacher turned to the 

 first boy at the right hand termination of the first row, and 

 inquired of him "How old are you?" Then, so soon as the 

 reply came, rapidly to the second boy seated next to the first 

 one: "And you?" and so on to the last of the twenty-five 

 scholars. A few minutes later the visitor inquired what social 

 position the children's parents occupied, and the process of 

 complete enumeration was repeated. In scientific activities the 

 completest enumeration of classes is habitually resorted to where 

 feasible, as for instance in the subjoined example adverting to 

 Faraday's researches: "He subjected bodies of the most varied 

 qualities to the action of his magnet: mineral salts, acids, 

 alkalis, ethers, alcohols, aqueous solutions, glass, phosphorus, 

 resins, oils, essences, vegetable and animal tissues, and found 

 them all amenable to magnetic influences. No known solid or 

 liquid proved insensible to the magnetic power when developed 

 in sufficient strength. All the tissues of the human body, the 

 blood though it contains iron included, were proved to be 

 diamagnetic." (Tyndall, Faraday as a Discoverer, p. 91.) 1 Not 

 a few scientists would profit incalculably if they decided on 

 as large a survey of their subject as Bacon undertook when 

 examining the nature of heat, and the day is surely near when 

 methodologists will be agreed in the demand that Bacon's 

 example should be universally imitated where the facts are 

 ascertainable with fair ease. For instance, instead of stating 

 in a serious discussion that the great facts of life are nutrition, 

 growth, and reproduction, we ought to enumerate all the leading 

 factors: irritability, contractility, nutrition, adaptation, regene- 

 ration, growth, senescence, death, reproduction, variation, here- 

 dity, and evolution. 



1 "All this Newton accomplished by the simple and elegant contrivance 

 of enclosing in a hollow pendulum the same weights of a great number of 

 substances the most different that could be found in all respects, as gold, 

 <*la<=*, wood, water, wheat, etc. . . ." (Herschel, Discourse, [179.].) 



"Ramsay, in conjunction with Travers, spent several years in a hunt for 

 the missing elements. They heated upwards of a hundred minerals. . . . 

 Mineral waters were boiled, so as to expel dissolved gases. . . . Even meteo- 

 rites . . . were heated." (Sir William Ramsay, Essays Biographical and 

 Chemical, 1908, p. 153.) "By the analysis of an almost incredibly large 

 number of compounds, he [Berzelius] established on a firm basis the con- 

 stancy of the composition of compounds, and the law of multiple proportions." 

 (Ibid., p. 162.) To ascertain the systematic motion of stars, we are told in 

 the Report of the British Association for the Advancement of Science for 

 1908, 1800 stars from all the parts of the sky were examined (p. 604). "In 

 the year 1900, M. and Mme. Curie made a systematic search of these 

 effects in a great number of chemical elements and compounds and in many 

 natural minerals." (Whetham, The Recent Development of Physical Science, 

 pp. 200-201.) 



"So fand Kepler sein drittes Gesetz, dass die Quadrate der Umlaufszeiten 

 der Planeten sich verhalten wie die Wiirfel ihrer mittleren Entfernungen 

 von der Sonne, durch eine vollstandige Induction, namlich durch eine Ver- 

 gleifhung der mittleren AbstSnde aller damals bekannten Planeten von der 



