October i i, 1894] 



NA TURE 



577 



(Lord Kelvin) and his successors. Motion on a rotating 

 globe ; Ferrel's and other simple approximate relations 

 ^Between baric gradients and the wind and temperature ; 

 /Ferrel's general circulation of the atmosphere and his 

 f cyclones and pericyclones and tornados. Galton's 

 cyclone and anticyclone. Fourier's most general 

 equations of gaseous motions. Uberbeck's general cir- 

 ifial^'on. Helmholtz's horizontal rolls. The investi- 

 gations of Diro Kitao, Guldberg and Mohn, Marchi, 

 Boussinesq, A. Poincare, Sprung, Siemens, Moeller, 

 Ritter, and others into the motions of the atmosphere. 

 Viscosity and discontinuous movements. The possible 

 special solutions of the general equations of fluid motions 

 that apply to the true atmospheric circulation, both on 

 the earth and on the other planets. Atmospheric tides ; 

 theories of Laplace, Ferrel, Rayleigh, Margules, A. 

 Poincare. Theories of atmospheric electricity. 



Time. — Eighty lectures and an additional four hours a 

 week given to special reading and investigation, and to 

 the preparation of the final thesis, as closing the four 

 years' course. 



Concomitant Studies. — Riemann's " DiH"erenti al 

 Gleichungen " ; Auerbach's " Hydrodynamics ' ; Lamb's 

 " Fluid Motions " (new edition) ; physical lauoratory 

 work in gaseous motions, optical and electrical 

 phenomena. 



THE ROYAL PHOTOGRAPHIC SOCIETY. 



SIR H. TRUE^L4N WOOD, the new President of 

 the Royal Photographic Society, delivered an 

 address at the opening meeting of the present session 

 on Tuesday. After briefly tracing the development of 

 the Society, he said : 



" Turning aside from the consideration of the affairs 

 of our own Society, to the general condition of photo- 

 graphy, we find cause for nothing but congratulation. 

 It is not so very long since photography occupied a 

 very subordinate position in the world alike of science 

 and of art. Scientific men looked oa photography as a 

 mere art, artists regarded it as a mere science. About 

 twenty years ago, when 1 suggested that some improve- 

 ment in a photographic process — I I'orget now which 

 — ought to be brought before the Physical Section of 

 the British Association, I was told that there was nothing 

 scientific about photography, that it was a mere empirical 

 pursuit, unworthy the attention of serious students of 

 science. 



" And to a large extent the reproach was well de- 

 served. Though the list of the earliest workers in 

 photography contains many illustrious names, yet it is 

 true that a large proportion of the most important con- 

 tributions to photographic knowledge were not made by 

 scientific workers, or by men who worked in scientific 

 methods. They were obtained .by practical men, seek- 

 ing for results ; often, indeed, seeking for them success- 

 fully by methods which would not have commended 

 themselves to men better equipped with scientific know- 

 ledge. Of course this was the consequence of the fact 

 that photographic science was early associated with pho- 

 tographic practice ; and the same remark holds good of 

 other sciences, electricity for instance, in which theory 

 and application to practical use advance with equal 

 steps ; but I think it applies more to photography than 

 to any other. 



" At the present time we have indeed reached a very 

 different condition of things. .Ml the most striking of 

 the recent advances in the science arc the result of 

 elaborate scientific research. The most recent improve- 

 ments in lenses were the fruit of long and laborious 

 investigation into the optical properties and the chemical 

 nature of certain sorts of glass. The increased speed 

 of modern plates, and their improved power of render- 

 ing colour values more truly, have only been obtained 



NO. 1302, VOL. 50] 



by minute knowledge of the condition of the problem 

 to be solved, and by careful application of the most 

 recent results of chemical and physical research. If 

 the old photographic crux, the reproduction of colour, 

 has been solved, or, at all events, if a possible method 

 has been indicated for its solution, it was not by hap- 

 hazard experiment, but by careful adjustment of means 

 to secure an anticipated result. Nowadays, we can only 

 hope for improvement by utilising the advance of 

 scientific knowledge. 



" But if the present position of photography is due to 

 progress in the kindred sciences, how amply has she 

 repaid the debt ! There is not a single branch of science 

 in which photography is not largely used. There are 

 many whose progress is now absolutely dependent on 

 the power of the camera to observe more accurately, 

 more independently, more minutely, more rapidly, more 

 permanently, than the human eye. If, as appears to be 

 the case, we have reached the limits of human vision, 

 aided by the most delicate instruments that can be 

 constructed, it is difficult to imagine what limits need be 

 set to photographic vision, can we but construct 

 instruments of accuracy sufficient to allow its full powers 

 to be utilised. 



" I imagine that the first application of photography to 

 a scientific purpose must have been when Dr. Draper in 

 New York photographed the moon. Whether the 

 pictures he obtained were of any astronomical value, I 

 do not know ; certainly those taken a little later, in 1852, 

 by Dr. W'arren De la Rue, were, and they were the 

 precursors of the long series of astronomical photographs 

 culminating in Dr. Common's nebula of Orion, and in 

 the great work of charting the heavens by photography 

 which is now in progress. 



" The advantages of the 'retina which never forgets,' 

 and it might be added which never tires, which 

 accumulates weak impressions and stores them up till 

 they become one strong one, were long since recognised 

 by be la Rue, and I suppose it will not be very long 

 before, for astronomical purposes, eye observations are 

 entirely superseded by photographic. The photographic 

 camera is now an indispensable adjunct to every large 

 telescope, if indeed it would not be equally correct to say 

 that the telescope is an adjunct to the camera, since the 

 astronomical telescope tends more and more to assimilate 

 to the form adopted long since by Mr. Rutherford, in 

 which the visual rays are treited of but slight importance, 

 and the chief attention is given to the accurate utilisation 

 of the more chemically active rays at the violet end of 

 the spectrum.' 



" In his recent address to the Photographic Conven- 

 tion at Dublin, Sir Howard Grubb, than whom nobody 

 is better qualified to speak on the subject, dwelt on the 

 services which photography has rendered to astronomy, 

 and gave several striking illustrations of those services. 

 Indeed, if one not qualified to speak on such matters 

 with any authority might hazard an opinion, it would 

 almost seem as if the power of recording observations 

 had already outstripped the capacity for examining the 

 observations, and drawing conclusions from them. When 

 we are told that a photographic plate has recorded 10,000 

 stars in an area not containing a single visible star, one 

 may be excused an expression of wonder as to how the 

 human mind is ever to grapple with problems of such 

 infinite complexity, to turn to useful account observations 

 dealing with such enormous multitudes. 



"But if the telescope has lately become one of the most 

 important of photographic appliances, the spectroscope 

 may be said to have held that position almost since its 

 introduction. Mr. Norman Lockyer, in his well-known 

 text- book, '■ Studies in Spectrum Analysis,' attributes to 



1 A good illustration of the tclescorc of the future Wvulii .H)i)f.Tr to be 

 the 24-inch photographic rcinxclor with an i8-inch visual telescope, 

 now being constructed at the evpcnsc of Mr. McLean for the C.'xpc 

 Observatory. 



