ii6 



NA TURE 



{Dec. I, 1887 



forget the many important investigations in mathematical physics 



■of which Kirchhoff was the author. 



The present year is memorable as the Jubilee of the reign of 

 Her Most Gracious Majesty our beloved Sovereign, and the 

 Patron of our Society. An address of congratulation on this 

 auspicious event was prepared by the Council, and was <jraciously 



o-eceived by Her Majesty in Windsor Castle at the hands of your 

 President, who was accompanied on that occasion by the senior 

 Secretary. 



It happens that this same year is also the Jubilee of the 

 Electric Telegraph, if we date from the first construction of 

 a telegraph on an actually working scale, as distinguished from 

 preparatory experiments made only in the laboratory. The 

 Jubilee was duly celebrated by the Society of Telegraph 

 Engineers. The name of our former Fellow Wheatstone will 

 go down to posterity as having occupied a foremost place in 

 this great practical application of Oersted's fertile discovery. 



I will just briefly allude to another outcome of scientific 

 research. The last half-century was well advanced when our 

 Fellow Dr. Perkin, by utilizing a colour reaction which had been 

 employed by chemists as a test for aniline, laid the foundation 

 of the industry of the coal-tar colours, which has now attained 

 such great proportions, and the investigation of the chemical 

 theory of which has occupied the attention of so many eminent 

 chemists from our own Fellow Dr. Hofmann onwards. 



There is yet another Jubilee connected with this same year in 

 which our Society is if posible still more closely connected : it 

 is now just 200 years since the publication of the first edition of 

 that immortal work, "The Principia" of Newton. Some of 

 the important results embodied in the Principia had previously 

 Ijeen communicated to the Royal Society. 



But, restricting our view to the last half-century alone, we can 

 hardly help casting a glance at the progress of science, and of the 

 practical applications of science, within that period. In electricity, 

 I have already referred to the electric telegraph, now passed into 



. the management of a department of the State, and inwoven in our 

 daily life, with its wires stretching all round the earth like the 

 nerves in the body, and placing us in immediate connection with 

 distant countries. Much more recent than the invention of the 

 electric telegraph is that, in some respects, still more wonderful 



■ apparatus for communication at a distance afforded by the 

 telephone. The application of electricity to lighting purposes, 

 of which we have availed ourselves for the lighting of the apart- 

 ments of our own Society, is an industrial outcome of Faraday's 



• discovery of magneto-electric induction which could not have 

 been thought of when the account of that discovery first ap- 

 peared in our Transactions. It is true that what I have just 

 been mentioning with respect to e'ectricity consists of industrial 

 applications rather than the discovery of new scientific prin- 

 ciples ; but these industrial applications react upon abstract 

 science beneficially in more ways than one. The possibility of 

 useful applications induces theorists to engage in investigations 

 which they might not otherwise have thought of, the result of 



• which is oftentimes to lead them to a clearer apprehension of 

 fundamental principles, and to induce them to undertake exact 

 quantitative determinations of fundamental constants. More- 

 over, the grand scale on which apparatus for actual commercial 

 use has to be constructed renders it possible for scientific men, 

 through the courtesy of those who direct the construction, to 

 make interesting experiments on a scale the cost of which would 

 be quite prohibitory if it were a matter of science pure and 

 simple. Take for example the experiments made by Faraday 

 on the first cable prepared for the attempt to span over the 

 Atlantic Ocean. 



When we think of the progress of science, both abstract and 

 applied, during the last half- century, we can hardly help specu- 

 lating as to the possible increase of scientific knowledge half a 

 ■ century hence. Perhaps we might be tempted to think that the 

 mine must have been so far worked that no great quantity of 

 precious ore can still be left, except what lies too deep for 

 human power to extract. Yet surely the progress of knowledge 

 in the past warns us against any hasty conclusion of the kind. 

 How often have accessions to our knowledge been made which 

 were quite unforeseen and quite unexpected, and how can we 

 say what great discovery may not be made at any moment, and 

 what a flood of light may not result from it ? 



In what direction such discoveries may be made, it would be 

 rash indeed to attempt to predict. Yet one cannot help thinking 

 of one or two cases in which we seem almost in touch of what 

 if we CDuld reach it would probably give us an insight into the 



processes of Nature of which we have little idea at present. Take 

 for example the theory of electricity as contrasted with the theory 

 of light. In the latter we have the laws of reflection and re- 

 fraction, which have long been known, the remarkable pheno- 

 menon of interference, the curious appearances which we 

 designate by phenomena of diffraction. But all these fall in the 

 most simple and natural way into their places when we have 

 arrived at the answer to the question. What is light? which 

 is furnished by the statement, Light consists in the undulations 

 of an elastic medium. But we are not at present able to give a 

 similar answer to the question, What is electricity ? The appro- 

 priate idea has yet to be found. We know a great deal about 

 its laws, and its connection with magnetism and chemical action ; 

 we are able to measure accurately physical constants relating to 

 it ; we make it subservient to the wants of daily life ; and yet we 

 are unable to answer the question what is it ? Could we only 

 give a definite answer to this question, it seems likely that the 

 production of electricity by friction, electrostatic attractions and 

 repulsions, the laws of electrodynamics, those of thermodynamics, 

 the nature of magnetism, and magneto-electric phenomena would 

 prove to be all simple deductions from the one fundamental idea. 

 Nay more : so closely is electricity related to chemical action, 

 that could we only clearly apprehend the nature of electricity, it 

 seems not unlikely that an unexpected flood of light might be 

 shed on chemical combination. 



Let me refer to one other instance in which a large accession 

 to our present knowledge seems not altogether hopeless. We 

 know that when an electric discharge is passed through a given 

 ga«, or between electrodes formed of a given substance, an 

 analysis of the spark reveals a usually complicated spectrum of 

 bright lines characteristic of the chemical substances present. 

 The arrangement of the lines in most cases seems capricious, 

 while in other instances we have repetitions of line-, or else 

 rhythmical flutings, indicative of law, though one of no simple 

 character. There can be no reasonable doubt that the periodic 

 times indicated by the bright lines seen in the spectrum are those 

 belonging to the component vibrations of the chemical molecules 

 themselves ; and the appearance is just such as would be pro- 

 duced by a tolerably complex dynamical system vibrating under 

 the action of internal forces of restitution. Now such a system 

 may really be composed of two or more simpler systems, held 

 together less firmly than the parts of one of the simpler systems ; 

 and the complex vibrations of the whole may be made up of those 

 of the several simpler systems, modified, however, by their mutual 

 connection, together it maybe with others due to the mutual con- 

 nection of the simpler systems regarded each as a whole. It is 

 conceivable that relations of chemical composition may thus be 

 pointed out even between substances which we deem elementary, 

 and which from their great stability we may, perhaps, never be 

 able actually to decompose. 



But I must apologize for having taken up your time with 

 speculations as to the future ; I will turn now to some mention 

 of the action of your Council during the past year, and of the 

 progress made by Committees appointed by the Council. 



In response to an invitation received from the Academy of 

 Sciences of Paris, that the Society should be represented at the 

 International Conference of Astronomers, which it was proposed 

 I should assemble in Paris, in the spring, for the purpose of de- 

 liberating about concerted action for obtaining a complete map 

 of the starry heavens by means of photography, your Council re- 

 quested the Astronomer Royal to represent the Society on that 

 occasion. The Conference met, as it was proposed, last spring ; 

 and I believe that the English astronomers at least think that a 

 good foundation has been laid for concerted action in that great 

 undertaking. 



As the Fellows are already aware from a circular which has 

 been issued, the Council has decided to make a change in the 

 mode of publication of the Philosophical Transactions. The 

 average yearly volume is a good deal more bulky now than it 

 was at the beginning of the century, and its size is such as not 

 unfrequently to make it desirable to bind one volume in two. 

 The sciences, moreover, which are represented in the Philo- 

 sophical Transactions, divide themselves very naturally into 

 two groups : mathematics, physics, and chemistry forming one, 

 and the biological sciences the other. The Council has decided 

 to issue the Transactions from henceforth in two series, cor- 

 responding to these two divisions, and a yearly volume will 

 appear in each series. It is hoped that this arrangement will be 

 conducive to an earlier publication, as the numeration of the 

 pages in the two series can go on independently. The indi- 



