512 



NATURE 



[x\uGUST 29, I918 



intermediate minima or to extend the ephemerides to 

 19 18 or later. The lists are practically confined to 

 stars visible in European latitudes. 



The Origin of Comets.— In an article which 

 appears in the August issue of Scientia (vol. xxiv., 

 p. 85), Prof. E. Stromgren gives an interesting account 

 of the reasons for regarding comets as permanent 

 members of the solar system. In recent years exact 

 calculations have shown that comets which have ap- 

 peared to traverse hyperbolic orbits, when in the 

 neighbourhood of the sun, acquired the hyperbolic 

 form in consequence of the perturbations to which 

 thev were subjected by the planets. It is accordingly 

 concluded that comets belong to our system, and that 

 the so-called non-periodic comets are merely comets 

 which have very long periods. The possibility of a 

 comet entering our system from without is not ex- 

 cluded, but it is stated that no case of this kind is 

 yet known. By reference to the dynamics of star- 

 clusters it is argued that, while remnants of nebulous 

 matter would, in general, be retained within the sys- 

 tems formed by individual suns, those which originally 

 occupied the intermediate spaces would escape from the 

 galactic system on account of the high velocities corre- 

 sponding with their small masses. On this view, 

 comet-forming materials would not exist in inter- 

 stellar space. 



Solar Physics Observatory Report. — The fifth 

 annual report of the director of the Solar Physics 

 Observatory, Cambridge, relating to the year ending 

 March 31 last has been received. A study has been 

 made of the South Kensington series of photographs 

 of the spectrum of (3 Lyrae, and information has been 

 gained as to the best epochs for further records with 

 comparison spectra. Further investigations of the 

 hydrocarbon-band lines in stellar spectra have indicated 

 a sequence in which there is a gradual strengthening 

 of the hydrocarbon lines from type F to type G, and 

 a gradual weakening of the same lines from the G to 

 the M type. Photographs of the sun's disc in calcium 

 light were obtained on 161 days, and of prominences 

 at the limb on 153 days ; the disc spectroheliograms 

 provide records for fourteen days which were missed 

 in the Kodaikanal series. Numerous photographs of 

 sunspot spectra were also obtained, and a comprehen- 

 sive table of the affected lines recorded by various 

 observers has been prepared. The necessity ^for a daily 

 reference photograph of the sun's disc has led to the 

 utilisation for this purpose of the image-lens of 60 ft. 

 focal length which forms part of the McClean solar 

 installation ; by the use of slow bromide paper the 

 photographs obtained have proved to be of greater 

 value than was anticipated, inasmuch as they present 

 the faculae as well near the centre of the disc as near 

 the limb. These photographs seem likely to be of 

 special value in the elucidation of the relation between 

 faculae and flocculi. Investigations connected with the 

 national defence have also been undertaken. 



BRITISH SCIENTIFIC INSTRUMENTS AND 

 PRODUCTS. 



(~\F the lectures delivered at the British Scientific 

 ^^ Products Exhibition, organised by the British 

 Science Guild at King's College, a feature common to 

 all is the disclosure of the backward state of the indus- 

 tries with which they were respectively concerned 

 when the war broke out. In radiology the outbreak of 

 war four years ago found a condition of unprepared- 

 ness in common with other branches of medicine. It 

 was necessary to provide large quantities of new 

 apparatus and the adequate staff for many new depart- 



NO. 2548, VOL. lOl] 



ments. This state of affairs was described by Dr. R. 

 j Knox in the course of « lecture on the practical uses 

 j of radiography ; and the backward state of the industry 

 which he described as prevailing four years ago is all 

 the more remarkable when we remember that 

 : although the X-rays were discovered by Prof . Rontgen,. 

 [ the discovery, as Mr. A. A. Campbell Swinton, who 

 ! presided at the lecture, pointed out. could never have 

 I been made but for previous scientific research carried 

 out in England. Had it not been for the work of 

 i Faraday, the necessary high-tension electric currents 

 , would not have been available, while the Crookes- 

 high-vacuum tube with which the rays were produced 

 I was the result of the laborious and long-continued 

 [ investigations of that veteran scientific explorer. Sir 

 i William Crookes, who, although eighty-six years of age,. 

 is still young enough to be an exhibitor at the exhibi- 

 tion. Mr. Campbell Swinton also pointed out that" the 

 two greatest advances made in connection with X-rays 

 since their original discovery were due in large 

 measure to professors at King's College, the original 

 Crookes " focus " tube having been adapted to X-ray 

 purposes by. Sir Herbert Jackson, and the recently in- 

 dented Coolidge tube, though brought out in the 

 United States of America, was based on the experi- 

 mental results obtained by Prof. O. W. Richardson, 

 also of King's College, working on lines laid down bv 

 Sir J. J. Thomson, of Cambridge 



Though the industry associated with radiography is 

 small, its importance is great and premises to become 

 greater in the future. Dr. Knox stated that experi- 

 ence gained in the administration of X-ray depart- 

 ments on a large scale, such as had been possible 

 during the past four years, had taught us the necessity 

 for a standardisation of apparatus. Had this been 

 achieved before the outbreak of war, as he considers 

 it well might have been, the task of rapidly equip- 

 ping numerous departments would have been 

 easy and the standard of work done much more 

 j satisfactory than it has been under the conditions 

 possible in war time. The lecturer emphasised the 

 need for research in connection with the production of 

 essential apparatus and X-ray tubes if we were to hold 

 our own in competition after the war. Most important 

 research work has been carried out in this country 

 lately in connection with the accessory apparatus, "and 

 Dr. Knox stated that the intensifying and fluorescent 

 screens at present in use are an advance on those we 

 formerly imported from German^^. The manufac- 

 turers of X-ray plates have more than held their own, 

 and the production of a trustworthy photographic 

 paper upon which X-ray negatives may be produced 

 directly is one of the achievements of the war period. 

 The most striking of the recent applications of X-rays 

 and radium described by Dr. Knox is that used bv 

 Mr. Percival P. Cole in connection with his operative 

 work on injury to the face and jaws, .\nother new 

 development in plastic surgery is also associated with 

 Mr. Cole's name, the well-known depilatory power of 

 X-rays having been used for the destruction of hair 

 in portions of the scalp and facs which are used in 

 plastic surgery. Dr. Knox insisted more than once 

 in the course of his lecture on the need for 

 1 encouraging research and bringing about the co- 

 1 operation of all interested in the work. He said that 

 ! steps are in progress with the view of forming a 

 \ British school of radiology and physicotherapy. 



In describing advances in bacteriologv during the 

 war. Dr. C. H. Browning, director of the Bland- 

 Sutton Institute of Pathology of tlie Middlesex Hos- 

 pital, mentioned that the need to overcome the poison 

 of sepsis in wounds had stimulated profitable investi- 

 gations on the properties of flavine and other dye- 

 stuffs as antiseptics. He emphasised the relation 



