THE STUDY OF SOCIOLOGY. 723 



tant discovery that the luminiferous undulations are lateral not longi- 

 tudinal, he says that it showed " a sagacity which would have done 

 honor to Newton himself." Just naming the discovery of latent heat 

 by Black, the discrimination by Wollaston of quantity and intensity 

 in electricity, and the disclosure of electrolysis by Nicholson and Car- 

 lisle (all of them cardinal discoveries) and passing over minor contri- 

 butions to physical science, we come to the great contributions of 

 Fai-aday magneto-electricity, the quantitative law of electrolysis, the 

 magnetization of light, and dia-magnetism : not mentioning others of 

 much significance. Next there is the great truth which men still liv- 

 ing have finally established the correlation and equivalence of the 

 physical forces. In the establishment of this truth Englishmen have 

 had a large share some think the larger share. Remembering that 

 in England the conception of heat as a mode of motion dates from 

 Bacon, by whom it is expressed with an insight that is marvellous 

 considering the knowledge of his time remembering, too, that 

 " Locke stated a similar view with singular felicity ; " we come, among 

 Englishmen of the present century, first to Davy, whose experiments 

 and arguments so conclusively supported those of Kumford ; then to 

 the view of Roget and the postulate on which Faraday habitually 

 reasoned, that all force arises only as other force is expended ; then 

 to the essay of Grove, in which the origin of the various forms of force 

 out of one another was abundantly exemplified ; and finally to the in 

 vestigations by which Joule established the quantitative relations be- 

 tween heat and motion. Without dwelling on the important deduc- 

 tions from this great truth made by Sir W. Thomson, Rankine, Tyn 

 dall, and others, I will merely draw attention to its highly-abstract 

 nature as again showing the baselessness of the above-quoted notion. 



Equally conclusive is the evidence when we pass to Chemistry. 

 The cardinal value of the step made by Dalton, in 1808, when the 

 aperpu of Higgins was reduced by him to a scientific form,' will be 

 seen on glancing into Wurtz's " Introduction to Chemical Philosophy," 

 and observing how the atomic theory underlies all subsequent chemi- 

 cal discovery. Nor, in more recent days, has the development of this 

 theory fallen unduly into foreign hands. Prof. Williamson, by recon- 

 ciling the theory of radicals with the theory of types, and by intro- 

 ducing the hypothesis of condensed molecular types, has taken a lead- 

 ing part in founding the modern views of chemical combinations. We 

 come next to the cardinal conception of atomicity. In 1851, Prof. 

 Frankland initiated the classification of the elements by their atomici- 

 ties: his important generalization being now avowedly accepted in 

 Germany by those who originally disputed it; as by Kolbe in his 

 "Moden der Modernen Chemie." On turning from the more general 

 chemical truths to the more special chemical truths, a like history 

 meets us. Davy's discovery of the metallic bases of the alkalies and 

 earths was an all-important step. Passing over many other achieve- 



