KNOWLEDGE & SCIENTIFIC NEWS. 



[May, 1905. 



is always some of the light which, striking water, is 

 neither Ecflected nor refracted, but simply scattered. 

 It may sound strange, though it is perfectly true, that 

 were it not for this scattering of light the surface of 

 water would never be seen at all, even in broad day. 

 It is just in the same way that the surface of a polished 

 mirror cannot be seen except where there may be some 

 scratch or smear upon it, and so true is this that in 

 unfamiliar houses we sometimes surprise ourselves by 

 walking up against walls which bear whole length 

 mirrors in unexpected places. In the photograph of 

 the sea bottom it will be noticed that the broken sur- 

 face of the sea is seen all over the picture, notwith- 

 standing the fact that through it all and below it all the 

 sea floor is seen also. 



Once below the surface, however, the ray travels 

 far more readily than is generallv sunnosed. The 

 swimmer who, in diving, is accustomed to open his 

 eyes under water is apt to imagine that very distinct 

 vision is out of the question, but he forgets that the 

 cause of this is due to the disturbance which his own 

 motion is causing in the water. A fish, on the other 

 hand, remaining motionless below, with an eye adapted 

 to its surroundings, may see remarkably well. And 

 on occasions it is brought home to the ordinary ob- 

 server how well light may pass into clear water, and 

 down to the depths below, and emerge again still in 

 strength enough to ensure good vision. This beautiful 

 phenomenon is particularly noticeable at the far end 

 of some of the Norwegian Fjords, where the sea water 

 has almost parted with its salt, and where no ap- 

 parent tides disturb the pure and peaceful depths. 



It is on looking down into these depths that one 

 curious and not unimportant fact has to be thought of, 

 namely, that they are much deeper than they seem to 

 be. This follows of necessity from what has been 

 already said, namely, that a ray whose path lies partly 

 in air and partly in water takes but a shallow cour.se 

 through the water, a truth which is made perfectly 

 apparent by simply dipping a stick or finger into a 

 basin of water. 



An amusing example of this illusion was forcibly 

 impressed upon a friend of the writer, who went to 

 take a morning dip in the swimming bath of an hotel. 

 The hour being early, no one was about, and being 

 long unfamiliar with baths of that description, he took 

 his plunge at an end where the depth appeared per- 

 fectly shallow. To his surprise, however, he found 

 himself the next moment in seven feet of water, and 

 then, and not till then, the teaching of his Cambridge 

 days came back to him, and he reproached himself that 

 he had not known better. For the rest it mattered 

 not, for in those olden days Cambridge had not known 

 a .stouter swimmer, and, happily, ' that one art .so 

 foreign to man, when once learnt, never deserts him 

 more. 



Ra.diatiorv from Hydrogen 

 Peroxide. 



Much interest has been caused in Germany by the 

 statement that it was found that photographic plates 

 were affected by hydrogen peroxide, even though 

 -screened by thin sheets of metal. It has been sug- 

 gested, on the other hand, that the hydrogen peroxide 

 IS capable of penetrating such screens through minute 

 and inperceptible holes. 



TKe Intern aLtiorvQLl 



CoLtaLlogue of Scientific 



LiteroLtvire. 



"The International Catalogue of Scientific Litera- 

 ture," published for the International Council, by the 

 Royal Society, London — Harrison and Sons. 17 vols. 

 Svo. Price, ^18. 



It is probably known to most of our readers that one of 

 the greatest difficulties encountered in these days by 

 workers in all branches of science is to ascertain what 

 their fellow-w-orkers have lately done and are now doing. 

 This difficulty is greatly increased by the enormous 

 number of scientific periodicals published all over the 

 world. Besides the numerous journals devoted to special 

 subjects, every museum and other scientific institution 

 issues its own "Proceedings" or " Transactions," which 

 often contain scientific information of the most varied 

 character. Taking Zoology, for example, we find in the 

 last volume of the " Zoological Record " a list of the titles 

 upwards of a thousand periodicals devoted to that 

 science alone, and in other branches of science there is 

 probably a corresponding number of publications of this 

 sort, which have to be carefully studied, in order to find 

 out who is working, and what has been written on any 

 particular subject. It is obvious, therefore, that even a 

 catalogue of the titles of published books and papers 

 would be a very great assistance to workers in science. 



The idea of forming such a catalogue of scientific books 

 and papers seems to have been first entertained in modern 

 days by the late Dr. Joseph Henry, Secretary of the 

 Smithsonian Institution at Washington. Dr. Henry 

 sent a communication to the meeting of the British 

 Association at Glasgow in 1855, suggesting the formation 

 of a catalogue of Philosophical Memoirs, which was 

 favourably reported upon by a committee appointed to 

 consider it. Two years later, in 1857, the late General 

 Sabine brought the subject before the Royal Society, 

 and requested the co-operation of that Society with the 

 British Association on this matter, .\fter some negotia 

 tions the Royal Society ultimately took up the undertaking 

 seriously and published the first volume of their catalogue 

 of scientific papers in 1867. This was subsequently con- 

 tinued until there are now twelve large (juarterly volumes 

 which contain the titles, alphabetically arranged accord- 

 ing to the authors' names, of all the scientific papers 

 published from 1800 to 1885. On referring to the last 

 report of the Council of the Royal Society we find it 

 announced that the great work of completing this cata- 

 logue to the end of k^oo is now making rapid progress, 

 but that the vast bulk of the material to he dealt with 

 has much delayed its issue. When it is finished it will 

 make the " Catalogue of Scientific Papers" complete 

 up to the end of the last century. 



The question of the best mode of ensuring the con- 

 tinuance of the catalogue during the present century, 

 having been maturely considered by the Council of the 

 Royal Society, it was determined that this arduous task 

 could best be carried out by the mutual co-operation of 

 all the nations interested in the progress of modern 

 science, and an International Conference w'as conse- 

 quently summoned by the Royal Society to consider the 

 question. This Conference took place in London in 

 July, 1896, and was attended by delegates from twenty- 

 one countries. It was unanimously agreed by all the 

 delegates that an " International Catalogue of Scientific 



