4o8 



NATURE 



\A71gust 28, 1879 



making tlie appeal to the senses, and there are others in which 

 the main difficulty lies in the process of reasoning. 



To contend with these difficulties successfully requires very 

 different qualities of mind and body. In experimental science 

 the powers principally called into requisition are readiness and 

 •closeness of observation, dexterity in manipulation, sldll in de- 

 vising expedients, accuracy in making adjustments, and great 

 patience. It also requires that the investigator should have an 

 accurate memory of what else he has witnessed resembling the 

 phenomenon under observation, that he should be quick to 

 detect every point of agreement and difference that can be per- 

 ceived, and be skilful to select those which are significant and 

 to employ them as materials for prevision to guide his further 

 proceedings. But the strain on the reasoning powers is gene- 

 rally less, often of trifling amount. The question is put to 

 Nature, and it is Nature usually that gives the bulk of the 

 answer. The most striking monument of splendid achievements 

 by the experimental method of investigation unaided by the 

 deductive method is to be found in the science of chemistry. 



An equally typical instance of the po^^•er of the deductive 

 method is the science of mechanics. This science, which has 

 sunk deeper into the secrets of Nature than any other science, 

 and which is the science towards which all other physical 

 sciences are at present more or less gravitating, is essentially 

 deductive. There is little or no difficulty about its fundamental 

 data. They are facts of Nature, so patent to all men, and so 

 indelibly implanted in human conception, that some persons have 

 supposed that we have an intuitive perception of them. But, 

 while the materials from which the mind is to work are thus 

 easily obtained, it has taxed to the utmost the reasoning powers 

 of understandings like Newton's to evolve the few consequences 

 of them which are already known, and the investigator has to 

 call to his assistance every aid to prolonged consecutive thought 

 Vfhich mathematicians can devise. 



In grappling with the problems of Nature we are seldom 

 allowed the choice of the method of investigation we shall 

 employ. This is commonly settled for us and not by us. Where 

 we cannot advance without further information, we must make 

 further observations, i.e., we must employ the experimental 

 method, the appeal ad experientiam ; where we cannot advance 

 without understanding better what the information we possess 

 really amounts to, we must employ the deductive method. . . . 



After referring to Kirchhoff's investigations as an example 

 Prof. Stoney said : — Wherever data are known exactly, there 

 inferences from these data, however remote, may be depended 

 upon as corresponding with what actually occurs in nature. 

 And if, in such cases, the mind of man has proved equal to the 

 task of drawing inferences which can effectually grapple with 

 the problems he finds around him in the universe — which is, 

 alas, as yet but too seldom — then will the deductive method, 

 our plummet, explore depths in the great ocean of existence 

 which our anchors of experiment could not have reached. 



The distinction which is here made between deductive and ex- 

 perimental investigations would have no place in a logical system. 

 But it has direct reference to human convenience, and derives its 

 importance from this circumstance. It is obvious, too, that an 

 investigation may partake of both characters — that it may require 

 all the powers of the scientific observer to get at the facts, or 

 even to appreciate them, and all the resources of the mathema- 

 tician to elicit the consequences of them. For instance, on be- 

 ginning his electrical studies the student of nature must master a 

 mixed experimental and deductive inquiry to get at the. ele- 

 mentary fact that free electricity resides either at or outside the 

 siu-faces of conductors ; and he must engage in a further inquiry, 

 and one only within the reach of a trained mind, to deduce from 

 this the lavi- of the inverse square. And, again, no full appre- 

 ciation or even intelligent use of the common electrostatic and 

 electrodynamic measures, which he meets at the threshold of his 

 electrical 'studies, is within the reach of the mere experimentalist 

 or of the mere theorist. And if this treacherous ground lies before 

 the immature student at his entrance, what shall we say of the 

 bogs he struggles into as he advances? We are perpetually 

 meeting with inquiries of this mixed character in electricity and 

 some of the other physical sciences, but they are comparatively 

 rare in either mechanics or chemistry, and none that is difficult 

 lies in the path of the beginner. How many students are there 

 who are made to slur over the above and a multitude of similar 

 difficulties, and who are told that they are learning science, when 

 in fact what they are really learning is the pernicious habit of 

 being content to see nature through a fog or through other men's 

 mental eyes. 



In mechanics valuable progress can be made by the mere malhe- 

 matician, the student of deductive science ; and in chemistry 

 similar progress can be made by the mere experimentalist. Of 

 all the physical sciences these are the most purely deductive and 

 the most purely experimental. What I desire particularly to 

 invite attention to is that the two great methods of investigation 

 may best be acquired in these two sciences, and that for a really 

 sound grasp of the remaining physical sciences, and especially 

 with a view to further advance in physical science, a command 

 of both methods of investigation is essential. But then, • to 

 bestow this invaluable power on the scientific student, the great 

 science of mechanics must be presented to him in its own true 

 form, and not degraded by the vile art of avoiding the legitimate 

 use of the infinitesimal calculus in order to comply with the ill- 

 judged conditions of some examination ; and our practical che- 

 mistry must be made something more scientific than instruction 

 in the lucrative art of the analyst. 



We must bear in mind, too, that either method of investiga- 

 tion may be misapplied, and that this is a risk carefully to be 

 guarded against. The deductive method, when misapplied, 

 lands us in speculation, the experimental method becomes em- 

 piricism ; and it so happens that the sciences of mechanics and 

 chemistry are not only monuments of the power of the two great 

 methods of investigation, but instructive examples of their weak- 

 ness also. For in chemistry scarce any attempt at prolonged 

 reasoning, carrying us by any lengthened flight to a distance 

 from the experiments, can be relied on. The result has seldom 

 risen to anything better than speculation. And on the other 

 hand, in mechanics conclusions which dei>end on experiments 

 only are empirical ; that is, they are deficient in accuracy and 

 their relation to the other phenomena of the science is left in 

 darkness. Here, then, we find in these two sciences not only 

 how strong these two methods of investigation are, but how- 

 weak they may become if misapplied. . . . 



I have sought to show that it is in the study of mechanics and 

 the practice of chemistry that the two great methods of investi- 

 gation may best be acquired. In them they may be studied 

 separately, by steps of graduated difficulty, and with a super- 

 abundance of materials ; and each of them supplies the necessary 

 cautions with respect to the method which is all-powerful in the 

 other. No scientific man is really equipped for the pursuits in 

 which both methods have to be employed till he has separately 

 acquired a grasp of each. For it is only then that he will be 

 armed against the errors which lead so many to mistake empiricism 

 on the one hand and speculation on the other for solid science, 

 or to underrate solid science, mistaking it for speculation. Nor 

 is it only in his scientific occupations that he will derive benefit 

 from this training. All exact reasoning, whether in science or 

 in common ^life, belongs to these great divisions ; and in the 

 numberless instances in which we must be satisfied with reasoning 

 which falls short of being exact, our only safety lies in having by 

 the practice of exact reasoning, both deductive and experimental, 

 attained to that intellectual tact and caution which alone will 

 enable us to handle with safety the sharp and slippery tool. It 

 is thus I am persuaded that a sound judgment with regard to 

 truth may best be acquired by man or woman ; and soundness 

 of judgment is the noblest endowment of man's understanding, 

 just as veracity is first among his virtues. 



SECTION D 



BIOLOGY 

 Department of Anatomy and Physiology 



Address BY P. H. Pye-Smith, B.A., M.D., Vice-President 



OF THE Section 



The Association to which we belong seeks to advance 

 Natural Science, that is, accurate knowledge of the material 

 world, by the following means : — 



First. — By bringing together men who are engaged in the 

 various fields of science indicated by our several sections, by 

 promoting friendship between them, by giving opportunity for 

 discussion on points of difference, by encouraging obscure but 

 genuine labourers with the applause of the leaders whom they 

 have learnt to venerate, and by fostering that feeling of resi^ect 

 for other branches of science, that knowledge of and interest 

 in their progress, which chiefly marks the liberality of scientific 

 study. 



Secondly.— The Association provides funds, which, though 



