SCIENCE. 



up of the iron into simpler constituents ? Mr. Lockyer 

 went on to state that the probability that the elements 

 are so broken up by the intense heat of the lower regions 

 of the solar atmosphere is increased by finding that many 

 of the lines seen in the lower regions are common to 

 more than one element. He did not believe that the 

 bright lines seen at the beginning and end of totality 

 which are frequently spoken of as belonging to the revers- 

 ing layer correspond toihe dark lines of the Frauenholer 

 spectrum. In witnessing another total eclipse he should 

 concentrate his attention on two of the basic iron lines, 

 and note their behavior at the instant of totality. 



Mr. Ranyard said : It is some years since we have seen 

 Mr. Lockyer at a meeting of the Society. I am glad to 

 see him here again, not only for the sake of the very elo- 

 quent lecture which he has given us, but also because of 

 the influence which a Society like this is likely to have on 

 those who read papers before it. It gives an opportunity 

 of criticising theories and of asking questions, which is 

 no doubt beneficial to the person who brings the theories 

 forward. Mr. Lockyer has referred to a theory, which 

 he has very widely discussed, with regard to the non- 

 elementary nature ot the elements, and the evidence to 

 be derived from solar observations, I understood him to 

 say that he would expect a greater heat to give us a less 

 complex spectrum. 



Mr. Lockyer : I never said anything of the kind. 



Mr. Ranyard ; I was about to say that the reverse ap- 

 pears to be the case. I hope that Mr. Lockyer will after- 

 wards take the opportunity of explaining what he means. 

 The spectrum of the photosphere is very complicated as 

 compared with the spectrum ot sunspots and prominences. 

 If any fact needs dwelling upon with respect to the sun, 

 it is the number of lines which cannot be matched with 

 terrestrial elements, and the complication of the spectrum 

 increases as you proceed downwards to the sun's limb ; 

 that is, as you proceed from cooler to warmer regions. 

 In the region of the Corona, very few lines have been 

 observed ; that may be, it is true, because of their faint- 

 ness ; but with the exception of the hydrogen lines, the 

 lines seen in the specttum of the Corona, which, of 

 course, is much cooler than the region of the chromo- 

 sphere, do not correspond to known lines of any terres- 

 trial element. There is, of course, an enormous field for 

 study here ; but the fact which I want to point out, is 

 that you do not get a simplified spectrum in the sun with 

 greater heat, and if the facts which Mr. Lockyer has 

 referred to with regard to the common lines in the spectra 

 of different elements are to be relied upon, it will not fol- 

 low that the common lines correspond to the similar 

 parts of the two elements, and that the other lines corre- 

 spond to mere overtones, given out with greater heat. 

 But I should like to ask Mr. Lockyer whether he has 

 taken note of the observations of Professor Young, who 

 has examined these lines common to two or more ele- 

 ments in the solar spectrum with great dispersion, and 

 has found that they nearly all break up into double lines 

 or groups of lines. I think out of fifty-seven lines all but 

 four were shown to be thus broken up, and there was 

 some doubt about these four. 



Mr. Christie said : Similar observations to those which 

 Mr. Lockyer has described with regard to the spectra of 

 Sunspots have been made at Greenwich, and without 

 adopting his theory, I may say that our observations 

 agree with those which have been made by Mr. Lock- 

 yer. We have not confined our attention merely to the 

 iron-lines which are thickened in the spot spectrum. But 

 we perfectly confirm what Mr. Lockyer says, namely that 

 in the spectrum of one spot there is one group of iron- 

 lines thickened, while in the spectrum of another spot, 

 there will be an altogether different group affected. 



Terrestrial Magnetism. — The French Government are 

 about to establish an observatory for terrestrial magnetism 

 at Cape Horn. 



A NEW DISCOVERY IN PHOTOGRAPHY. 



At the last meeting of the Photographic Society of Gieat 

 Britain, Mr. L. Warnerke described the discovery he has 

 recently patented. The discovery he said consisted in the 

 fact that a gelatine plate submitted to pyrogallic acid be- 

 came insoluble in those parts acted upon by light, exactly 

 in the same way as gelatine was acted upon oy chromic 

 salts, the insolubility being in proportion to the amount of 

 light and the thickness of the gelatine. This property he 

 proposed to utilize in various ways. The drawback in trie 

 ordinary gelatine process was that unless the exposure were 

 very accurately limed there was considerable danger of 

 over-exposure, and, as intensification was very dilficult, 

 pictures by the gelatine process were otten interior to those 

 by collodion, by the new process he was, however, able 

 not only to intensify, but also to overcome the drawbacks 

 arising from over-exposure. The latter he effected by using 

 the emulsion on paper. He had found that no matter how 

 much the paper was over-exposed the picture — provided 

 the developer was restrained sufficiently — was not injured, 

 while in the case of the emulsion on glass there was not 

 only halation of the image, but a reversal also. The trans- 

 fer of the image from paper on to the glass was a very easy 

 matter. The paper was immersed in water and placed in 

 contact with a glass plate. The superfluous moisture was 

 removed by a squeegee, and the paper could then be stripped 

 off, leaving the tissue on the glass. Hot water was then ap- 

 plied, which dissolved all the gelatine not acted on by light, 

 together with the free bromide or soluble salts, and the image 

 was left upon the glass in relief. Intensification he effected 

 by mixing with the emulsion a coloring non-actinic matter, 

 which was not affected by silver. Aniline colors he had 

 found answered the purpose, and in that way special emul- 

 sion for special purposes could be prepared, that method 

 of preparation he ihought would be especially suitable for 

 magic-lantern slides. He claimed for his discovery that by 

 it relief could be obtained far more easily than by the or- 

 dinary bichromatised gelatine, and therefore it was espec- 

 ially suitable for the Woodburytype process. By mixing 

 emery-powder with the emulsion it was rendered fit for en- 

 graving purposes, and by a combination with vitrified colors 

 the image could be burnt in and so* was adapted for 

 enamels. In the ordinary methods of producing enamels 

 from carbonised gelatine the latter, from the difficulty of 

 burning rt without the formation ot bubbles, was a great 

 source of troubie. By using a suitable emulsion, however, 

 so little gelatine might be employed that this drawback was 

 overcome. The process could also be adapted for collotype 

 printing. In the course of his remarks, Mr. Warnerke 

 demonstrated the removal of a gelatine picture produced 

 by his method from paper on to glass, and showed that the 

 mere immersion and washing in hot water fixed the picture 

 by the dissolving of the gelatine unacted upon by light, 

 which thus carried away the tree bromide of silver, in con 

 elusion, he stated that the sensitive paper could be used in 

 the camera in lengths wound on rollers, and exhibited a 

 camera which he had made for the purpose. 



Captain Abney, after some remarks in reference to hala- 

 tion and reversal ot the image, remarked that in the pro- 

 duction of enamels by Mr. Warnerke's process there was 

 some danger of the silver producing the well-known yeliow 

 colour which spoilt so many vitrified photographs. The 

 discovery made by Mr. Warnerke was a most imponan 

 one, and in regard to Woodburytype, really opened up quite 

 a new era. Mr. W. S. Bird endorsed Captain Abney's re 

 marks as to the value of the process. To be able to pro 

 duce gelatine negatives without the fear of the yellow stain 

 was a great boon, and the only point was whether photo- 

 graphers would take the trouble and risk in the necessary 

 transfers. As to its adaptability to Woodburytype, there 

 could not be the slightest doubt. The great difficulty was 

 to obtain the necessary relief, and he knew of a company 

 which had recently gone to £. great expense to fit up the 

 necessary machinery, when Mr. Warnerke was able to givv 

 them what they wanted at a merely nominal cost. 



Mr. T. Sebastion Davis also referred to the importance 

 of the discovery, and suggested that by the use of the emul- 

 sion on paper a landscape might be photographed in which 

 the clouds and the foreground might be rendered with 

 equal truth, instead, as was too often the case, of the sky 



