NA TURE 



[December 7, 1899 



of alternating currents in conductors, he has made, in co-operation 

 with Mrs. Sidgwick, those classical investigations of the value of 

 the ohm in absolute measure, the electromotive force of the Clark 

 cell, the electrochemical equivalent of silver, and the specific 

 resistance of mercury. His researches on the theory of elas- 

 ticity are valued by all students of mathematical physics. In 

 his researches on the density of gases he met with small discrep- 

 ancies between the density of nitrogen derived from the air and 

 that derived from chemical compounds. Investigations into 

 the cause of this discrepancy, followed up with wonderful skill 

 and perseverance, led to the discovery of a new element (argon) 

 existing in large quantities in the atmosphere, and possessing 

 qualities of a very novel and remarkable kind. Lord Rayleigh's 

 researches, from the range of subjects they cover, their abund- 

 ance and their importance, have rarely been paralleled in the 

 history of physical science. 



|RoYAL Medals. 



One of the Royal Medals is conferred upon Prof. G. F. 

 Fitzgerald, for his brilliant contributions to Physics. 



A foremost position has been occupied by Prof. G. F. 

 Fitzgerald during the last twenty years in the domain of Radia- 

 tion and Electrical Theory. At the time when very few people had 

 definite notions of the changed aspects which these subjects 

 had assumed after Maxwell's theoretical advances, he was 

 prominent as an expositor and developer of the new views. 

 Thus his paper on " Electromagnetic Effects due to the Motion 

 of the Earth" {Trans. Roy. Dub. Soc, May 1882) was, per- 

 haps, the earliest explicit effort to bring the facts regarding the 

 astronomical aberration of light and general optical knowledge 

 as to the relation of the aether to moving matter, into relation 

 to electrical theory. Enough was there established, in both the 

 optical and the purely electrodynamic domain, to show that no 

 fundamental discrepancy was to be anticipated in the new point 

 of view. Again, his paper " On the Quantity of Energy trans- 

 ferred to the /Ether by a Variable Current " {loc. cit. November 

 1883), forms probably the earliest investigation of the field of 

 an electric radiator. The case explored is that of a uniform 

 current of periodically varying intensity ; but the historical sig- 

 nificance of the investigation is not impaired by the circumstance 

 that subsequent research has transferred the source of actual 

 radiation to the oscillations of the ions in the molecule. 

 Already, in the preceding year, reflecting that crucial evidence 

 with regard to the new standpoint of Maxwell was probably 

 to be sought only in the domain of radiation, he had pointed 

 to the oscillatory electric discharge in a condenser as a means 

 of obtaining actual electric radiation, if only the period of the 

 oscillations could be sufficiently reduced. Reference may also be 

 made to the paper " On a Model illustrating the Properties 

 of the ^ther" {Proc. Roy. Dub. Soc, January 1885), which 

 has been widely useful, owing to the very simple manner in 

 which the model — which is on the principle of Maxwell's own 

 idle-wheel representation — visualises a large range of relations 

 of the aether that had previously been amenable only to abstruse 

 mathematical representation. 



At an earlier period, Prof. Fitzgerald was occupied with 

 magneto-optic phenomena, particularly with the theoretical 

 bearing of Dr. Kerr's then recent discovery of the peculiarity 

 in the reflection of light from a magnetised substance. That 

 subject is considered at length, with restrictions, however, to 

 transparent media in the analysis, in the latter half of the 

 memoir, " On the Electromagnetic Theory of the Reflection and 

 Refraction of Light " {Phil. Trans., 1879). But the main 

 interest of this memoir consists, perhaps, in the dynamical for- 

 mulation of the electric theory of light on the basis of the Prin- 

 ciple of Least Action, and in the comparison of that theory with 

 the optical work of the author's countryman, MacCullagh. He 

 has thereby contributed to a broader appreciation of that writer's 

 position, and has shown that his theory of light, which was 

 reached inductively along purely optical lines, runs parallel, and 

 is, in fact, identical with the theory of Maxwell which presented 

 itself in the course of a far wider induction originating in the 

 domain of electrodynamics. The remark with which this me- 

 moir concludes, as to the advantage of " emancipating our 

 minds from the thraldom of a material aether," has not, perhaps, 

 yet lost all its force. 



Not the least of Prof. Fitzgerald's services has been his success 

 in guiding and energising an Irish School of Natural Philosophy. 

 His efforts, and those of his pupils, have had a prominent share 

 in the development and illustration in this country of the 



NC. T571, VOL. 61] 



phenomena of electric radiation. Thus, in 1889, he was en- 

 gaged, with Mr. F. T. Trouton, in verifying the laws of polari- 

 sation, by reflection, for Hertzian radiation ; in 1890, he brought 

 forward a new means of detecting such radiation by a galvano- 

 meter inserted across the spark-gap ; in 1892 he returns to the 

 problem of practical electric vibrators by a series of suggestions 

 as to ways in which a ^continuous vibration of the requisite 

 high frequency might possibly be established. He has experi- 

 mented, with Dr. Trouton, in 1896, on the scattering of Rontgen 

 radiation in passing through paraffin ; and, along with Mr.W. E. 

 Wilson, he has conducted a research on the effect of the pressure 

 of the surrounding atmosphere on the temperature of the electric 

 arc, which must have important bearings on the theory of 

 radiation from solid bodies. He has also completed the work 

 of Maxwell and Chrystal on Ohm's law of conduction by 

 minutely testing its validity for the case of electrolytes. 



More recently his efforts have contributed to the elucidation 

 of the modifications impressed on the lines of a radiant spec- 

 trum, by change of pressure of the atmosphere surrounding the 

 radiator, and by a field of magnetic force. 



His critical activity pervades an unbounded field, enlivened 

 and enriched throughout by the fruits of a luxuriant imagin- 

 ation. 



The other Royal Medal is given to Prof. William Car- 

 michael Mcintosh for his very important labours as a zoologist. 



Prof. Mcintosh may be regarded as one of a distinguished 

 succession of monographers of the British Fauna who, beginning 

 with Edward Forbes, have during the last fifty years done work 

 highly creditable to British Zoology. 



Mcintosh's great monograph of the British Annelids, pub- 

 lished by the Ray Society, is still in progress. Two folio 

 volumes appeared more than twenty years ago, a third is now 

 in the press, and a final volume is contemplated. As a result of 

 this work, and of numerous papers on the subject, Mcintosh 

 is justly regarded as the European authority on this group of 

 animals. But his work has by no means been wholly that of a 

 systematist. He is the author of one of the large and important 

 Challenger Reports (that on the Polychceta), and of several 

 minor reports of the same and other Government expeditions. 

 His other papers extend over a wide range of subjects, and deal 

 with many structural points. His name, moreover, is associated 

 with the discovery or the description of several of the more re- 

 markable or problematical of marine animals — such as Pelonaia, 

 Phoronis, and Cephalodiscus. 



Some of Prof. Mcintosh's earlier papers were on fishes and 

 their life history, and during the last ten or twelve years he has 

 returned to that subject, and has added to the knowledge of our 

 sea fisheries to a remarkable extent— both by observations 

 anatomical and embryological (published in the Trans. Roy. 

 Soc. Edin. ), and in his book on British marine fishes, and by 

 experiments on a large scale calculated to yield results of in- 

 dustrial importance. 



Finally, Prof. Mcintosh has been a notable teacher in Scot- 

 land, and many of those he has trained now occupy zoological 

 posts and have conducted important researches. He is himself 

 still a very active worker, both in his own investigations and in 

 directing the researches of others. He was the first to found a 

 marine biological station in this country, and the establishment 

 of the present well-known Gatty Marine Laboratory at St. 

 Andrews is entirely the outcome of his energy and influence. 

 Davy Medal. 



The Davy Medal is bestowed upon Edward Schunck for 

 researches of very high importance in Organic Chemistry. 



Edward Schunck is the author of a remarkable series of con- 

 tributions to the chemistry of vegetable colouring matters, 

 dating from 1841 up to the present time, and it is noteworthy 

 that his first English paper appeared in the first volume of 

 memoirs issued by the Chemical Society of London. 



His earlier work includes two investigations which are every- 

 where regarded as classical, the one relating to the Madder 

 plant, the other to the Indigo plant, from which the two most 

 important dye-stuffs known to us are derived. In these, besides 

 establishing the fact that the colouring matters are not present 

 as such in the plant, but as glucosides, he brought to light 

 much other information of importance in relation both to ali- 

 zarin and indigo, and to allied substances with which they are 

 associated. 



In 1871,5 by his discovery of anthroplavic acid in artificial 

 alizarin, he gave an important impetus to the further study of 



