156 



NA 7 UR£ 



[Dec. 24, 1874 



aliments which are supplied to it. He found that, in addition to 



cimmonia and sugar, the cells require mineral substances, such as 

 phosphates and other constituents, such as are present in the 

 organism of every healthy and growing yeast- cell. 



In short, he proved that those conditions which are most 

 favourable to the healthy growth and development of the yeast- 

 cells are most conducive to the progress of fermentation, and 

 that fermentation is impeded or arrested by those inlluences 

 vchich check the growth or destroy the vitality of the cell. 



The above results are but samples of the fruits of Pasteur's 

 long series of researches in this subject. Many and many an 

 able investigator had worked in the same field ; and such were 

 the difficulties they encountered, that Dumas himself recom- 

 mended Pasteur not to waste his^ time in working at so hopeless 

 a subject. 



To the biologist, two of Pasteur's researches are of very great 

 interest and importance. He has shown that f2(ngi find all the 

 materials needed for their nutrition and growth in water con- 

 taining an ammonia salt and certain mineral constituents, and 

 devoid of any nitrogenised organic matter ; and he has proved 

 that all the phenomena presented by the destructive sUkworm 

 epidemic, the pcbrmc (even the singular fact that it is heredi- 

 tarily transmitted through the female, and not through the male), 

 are to be explained by the presence of a parasitic organism in 

 the diseased caterpillars. 



The medal was received for Prof. Pasteur by the Foreign 

 Secretary of the Society. 



The Rumford Medal has been awarded to Mr. J. Norman 

 Lockyer, F.R.S., " for his Spectroscopic Researches on the Sun 

 and on the Chemical Elements." 



Mr. Lockyer has long been engaged in spectroscopic researches 

 on the sun. His first observations were directed to a scrutiny of 

 the spectrum of sun-spots as compared with that of the general 

 surface, with a view to bring evidence to decide between two 

 rival theories respecting their formation. In the course of the 

 paper in which his first observations were described, and which 

 was read before the Royal Society on November 15th, 1S66, he 

 asks, " May not the spectroscope afford us evidence of the ex- 

 istence of the ' red flames ' which total eclipses have revealed to 

 us in the sun's atmosphere, although they escape all other modes 

 of examination at other times?" 



The spectroscope he then employed proved to be of insufficient 

 dispersive power for his researches, and he was induced to apply 

 to the Government-Grant Committee of the Royal Society for 

 aid to construct one of greater power. This aid was accorded, 

 and the instrument was delivered, though not quite complete, on 

 the l6th of October, 1S68. On the 20th his efforts were crowned 

 by the detection of a solar prominence by means of the bright 

 lines exhibited in his spectrum. An account of this discovery 

 was immediately communicated to the Royal Society and to the 

 French Academy of Sciences. 



Meanwhile had occurred the total solar eclipse of August I Sth, 

 1868, to observe which various parties had gone out armed with 

 suitable instruments, and especially with spectroscopes, for de- 

 termining the character of the hilherto unknown spectrum of the 

 prominences ; and the first-fi'uits of their labours had reached 

 Furope, showing that the spectrum in question is one of bright 

 lines. It occurred to M. Janssen, who had observed with 

 eminent success the spectrum of the prominences during the 

 eclipse, that the same mode of observation might enable one to 

 detect them at any time, and he saw them in this manner the 

 very next day. '1 he first account of this discovery, which was 

 sent by post, did not, however, reach the French Academy until 

 a few days after the communication of Mr. Lockyer's notice ; so 

 that nothing interferes with the perfect independence with which 

 these two pnysicists established the possibility of detecting the 

 prominences at any time. 



A discovery like this opened up a new field of research, which 

 Mr. Lockyer was not backward in exploring. One of the first- 

 fruits of the application of the method was the discovery of a 

 continuous luminous gaseous envelope to the sun, which he calls 

 the chromosphere, of which the prominences are merely local 

 aggregations. Evidence was further obtained of gigantic con- 

 vulsions at the surface of the sun, which were revealed by slight 

 alterations of refrangibility in the lines, observed in a manner 

 similar to that in which Mr. Huggins had determined the relative 

 velocity of approach or recess ot tlie Earth and Sirius. 



The interpretation of spectroscopic solar phenomena requured 

 a re-examination in several respects of the spectroscopic features 

 of artificial sources of light. Among these researches special 

 mention must be made of Mv. Lockyer's classification of the lines 



due to the metals of the electrodes between which an induction 

 discharge was passed, according to their "length," i.e., the dis- 

 tance from the electrodes to which they could respectively be 

 traced. This led to the explanation of various apparent anoma- 

 lies as to the presence or absence of certain dark lines in the 

 solar spectrum, and to the detection of additional elements in the 

 sun, especially potassium, an element which, though so common 

 on the earth and so easily detected by spectral analysis, had not 

 previously been proved to exist in the sun, because the attention 

 of observers had been turned in a wrong direction, as was shown 

 by these researches. 



Nor was it only in relation to solar physics that these re- 

 searches bore fruit. They led to a quatititative determination in 

 many cases, by means of the spectroscope, of the proportion ot 

 the constituents in an alloy, and afforded new evidence of the 

 extent to which impurities are present even in substances deemed 

 chemically pure. 



The medal was received by Mr. Lockyer. 



A Royal Medal has been awarded to Mr. Henry Clifton Sorby, 

 F.R.S., " for his researches on slaty cleavage and on the minute 

 structure of minerals and rocks ; for the construction of the 

 Micro-Spectroscope, and for his researches on colouring- 

 matters." 



The principal grounds on which Mr. Sorby's claims to a Royal 

 Medal rest are the following : — 



1. His long-continued study, and his. successful application ot 

 the microscope to the solution of problems in petrology. 



2. His employment of the prism in conjunction with the 

 microscope for the analysis of the colours transmitted by sub- 

 stances, as well organic as inorganic. 



Though Mr. Sorby's labours during the last ten years have 

 been more particularly devoted to observations of the latter class, 

 his work, extending over a period that commenced in 1849, is 

 represented in the Catalogue of Scientific Papers (limited by the 

 year 1S63) by no less than forty-seven memoirs. Among the 

 more remarkable of these must be mentioned the reports to the 

 British Association and the contributions to the Philosophical 

 Ma'^a^iiw (1S53, 1S56, 1S57), in which he gr.rppled with the 

 subje :t of slaty cleavage, and helped to establish the explanation 

 that cleavage was the result of greater relative condensation ot 

 the material in a direction perpendicular to the cleavage, due in 

 the case of rocks to mechanical compression in that direction — • 

 an idea that met with immediate illustration from other experi- 

 mentalists. 



His memoirs on the temperatures and pressures at which 

 certain rocks and minerals were formed (in the Geological 

 Society's Jounial, 1S58), founded on the relative volume of the 

 liquid and vacuous portions of microscopic hollows, or, again, on 

 the character of microscopic substances mingled with the mineral 

 matter he investigated, convinced the geologist that he had to 

 take into account the action of water under high pressures and at 

 high temperatures in explaining the formation of granitoid rocks. 

 And the refinement of the methods that Mr. .Sorby employed 

 for making his rock-sections at Sheffield has made those methods 

 the models sought after by the now large school of Continental 

 and English microscopic petrologists. 



His applications ot spectroscopic methods to the microscope 

 fall more strictly within the limit of ten years, as they have been 

 worked out since 1S67, when i\Ir. Sorby first described his adap- 

 tation of the spectroscope to the microscope, as carried out by 

 Mr. Browning. 



The observations he has made with this instrument, and gens- 

 rally by combining optical examination with the use of chemical 

 reagents, have e.<tended over a very wide range — such as the 

 recognition of blood-stains, of adulteration in wine, the means 

 of discriminating among the compounds of certain of the metals, 

 chiefly of zirconium, titanium, and uranium, by the aid of bio n- 

 pipe beads — and finally to the elucidation, to a considerable 

 extent, of the causes of the complexity in the tints exhibited by 

 plants in the different stages of development of their annual 

 folia^;e and flowers. 



These are only some of the more important of Mr. Sorby's 

 contributions to science ; and they are characterised by an un- 

 tiring application of the methods of experimental research to a 

 great variety of subjects suggested by a very ingenious and active 

 mind. 



The medal was received by Mr. Sorby. 



A Royal Medal has been awarded to Prof. William Crawford 

 Williamson, F.R.S., "for his contributions to Zoology and 

 Palaeontology, and especially for his investigation into the struc- 

 ture of the (ossil plants of the coil-ineasurej." 



