SECTION 12. HYPOTHESES. 93 



when we reflect that Dr. Joule had been preceded by Davy and 

 Rumford (who had already dimly apprehended the far-reaching 

 theory of the conservation of energy), and was followed by 

 Grove, Maier, Helmholtz, Clerk-Maxwell, and others, who more 

 and more fully developed the theory of the conservation of 

 energy, we shall not be surprised that there are few exceptions, 

 if any, to the rule to which we have here called attention.' 

 Mendelyeff admirably illustrates this law of co-operation in the 

 establishment of a comprehensive hypothesis or theory: "I con- 

 sider it well to observe that no law of nature, however general, 

 has been established all at once; its recognition is always 

 preceded by many presentiments; the establishment of a law, 

 however, does not take place when the first thought of it takes 

 form, or even when its significance is recognised, but only when 

 it has been confirmed by the results of experiment, which the 

 man of science must consider as the only proof of the correct- 

 ness of his conjectures and opinions. I, therefore, look upon 

 Roscoe . . . and others who verified the adaptability of the peri- 

 odic law to chemical facts as the true founders of the periodic 

 law, the further development of which still awaits many fresh 

 workers." (The Principles of Chemistry, 1905, pp. 18-19.)- 

 Whetham, referring to the interdependence in physical enquiries 

 as illustrated by recent theories relating to chemistry, magne- 

 tism, electricity, Rontgen rays, and radio-activity, remarks in the 

 same vein: "The slow and patient work of many observers 

 through long years often leads up to and suggests the particular 

 step from which follows, almost of necessity, the practical appli- 

 cation or the far-reaching theory." (The Recent Development 

 of Physical Science, p. 198.) And the same author alludes in 

 these terms to the slow historic development of instruments, 

 which are but objective hypotheses: "The spectroscope itself 

 illustrates the progressive triumph of modern science, for it is 

 the work neither of one man nor of one century. Its principles 

 have been developed gradually, and its construction elaborated 

 throughout a couple of hundred years." (Ibid., p. 297.) That 

 epoch-making ideas issue spontaneously from the minds of great 



1 Not only is one hypothesis frequently the product of many minds, but 

 in most instances the hypothesis undergoes a prolonged evolution in its 

 author's mind before it is communicated to the world. 



Numerous examples might be cited of the social origin of ideas. The 

 following is selected at haphazard, and others will be found scattered through- 

 out this volume: "Galton and Jager, Brooks and Nussbaum, Hertwig and 

 Herdman, Na'geli and Weismann, and others, have all contributed to making 

 the fact of continuity more precise. Hopeful also are the suggestions of 

 Jager, Berthold, Gautier, and Geddes, which make towards a chemical ex- 

 pression of the continuity between germ and germ." (Chambers' Encyc- 

 lopaedia, article "Heredity".) 



- Mendelyeff was preceded by Newbolt in 1864, and Lothar Meyer made 

 the same discovery as Mendelyeff in the same year, in 1869. See on the 

 periodic law, Charles L. Bloxam, Chemistry Inorganic and Organic, 1913, 

 and also the works of Thorpe, Soddy, and Crowther cited. 



