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498 THE PHOTOGRAPHIC NEWS. [July 10, 1891. their art could give them to make their beauties better known. His Worship concluded as follows : We welcome you, then, as devoted to most interesting and important work, and we trust you will like our city and neighbourhood well enough to repeat your visit. There is a fountain in Rome of which it is said that those who taste of its waters always desire to come again ; may your experience of this city of the springs be so pleasant as to give you the same desire. Mr. Bothamley said, in coming to Bath, the Convention were visiting a place intimately associated with the early history of photography, with Fox Talbot, and Herschel, the latter being the first to apply photography to scientific purposes. Mr. Bothamley then relinquished the chair to the President-elect, of whose qualifications for the office he spoke in eulogistic terms. Mr. Bedford, who mentioned that he was the first pro fessional photographer to occupy the position of president, then delivered the following address. PRESIDENTIAL Address. Five years have now elapsed since the first meeting of the Convention, and this, our sixth annual assembly, finds us in the city of Bath, built on the reputation of its healing waters, but of especial interest to us photographers as being in the neighbourhood of Lacock Abbey, the home of Henry Fox Talbot, and, undoubtedly, the first spot in the Kingdom ever depicted by the photographic camera. Since our last meeting at Chester, it certainly cannot be said that the general interest taken in photography has in any degree abated ; and, to assure ourselves of this, it is only necessary to point to the increasing number of societies and clubs which have sprung up all over the civilised world, to the spread of photographic literature and journalism, and, as a notable instance of the popularity of the art, to the successes claimed for the numerous exhibitions held at Liverpool, Vienna, and elsewhere. Photographic societies generally have been showing marked activity. Although the scheme for the formation of a photo graphic institute brought forward by the Photographic Society of Great Britain has at present met with little more than moral support, and it is now clear that there is no immediate prospect of carrying it out in its entirety, the recent acquisition by the Society of premises of its own places it in a position to offer to other societies a scheme of affiliation which promises many advantages, and which can hardly fail to work, in all cases where co-operation is desirable, to the mutual advantage of all, without in any way interfering with individual action. The new premises of the Camera Club are a monument to the energy and enterprise of its management, and the annually recurring conference of that body, as well as its periodical “ one-man ” exhibitions, reminds us, as in past years, of the good work it is doing. The Photo-Survey Council of Warwickshire—a body consti tuted out of the photographic societies of Birmingham and Warwickshire—is doing excellent work, and challenges friendly rivalry with other counties. It embraces archology, ethnology, geology, and botany, in addition to the ordinary work of recording the general appearance of the county at the present day. In speaking of advance in the science of photography, it is difficult to gauge the importance of discoveries which require time to develop their capabilities, and I shall very possibly pass over without notice germs of discoveries more important than those I shall mention. There can, however, be no doubt that, in the province of systematic or specialised investigation, Messrs. Hurter and Driffield, by the further prosecution of their researches into the effect of development on the ratio densities of negatives, and other photographic scientists in critically following them, have been doing most valuable work; and, when it is remembered that these investigations are only a first step towards the establishment of an absolute standard of sensitiveness, it is easy to appreciate the importance of the elimination of all errors of observation and measurement from their calculations. Perhaps the announcement of most interest to the photo graphic world has been that of M. Lippmann’s discovery of a means of representing by pure photography, and subsequently fixing, the colours of the spectrum. Possibly no discovery is ever announced in the present day without resorting to a long stretch of unscientific imagination, and this has certainly not been absent here ; but it seems that M. Lippman’s experiments have been guided by a theory propounded in 1887 by Lord Rayleigh, that the colours of Becquerel’s reproductions of the spectrum were possibly due to the action of stationary luminous waves, producing, in a nearly transparent sensitive film, a laminated structure which would copiously reflect the particular kinds of light which had produced them. The essentials, according to M. Lippmann, are the continuity or absence of granularity of the film, and the presence, during exposure, of a reflecting surface behind this film. Spectrum red, yellow, green, and blue have thus, it is said, been vividly reproduced and fixed ; but the process is not applicable, so far as can be foreseen, to the reproduction of impure or mixed colours. There seems to be plenty of scope for experiment in this direction, and, it may be added, plenty of scepticism as to the results obtained. A practical method of producing a direct positive from nature, or a reversed negative direct from another negative, has long been a desideratum, so that unusual importance attaches to the discovery, by Colonel Waterhouse, that the addition of a minute quantity of thio-carbamide or of thio-sinamine to the eikonogen developer has the effect, in favourable conditions, of effecting during development a complete reversal of the photographic image, and this with exposures one-tenth the duration of the normal. The substance he finds to answer the purpose best is Dr. J. Emerson Reynolds’ preparation of thio-carbamide with ammonium bromide, which is a combination of four molecules of the former substance with one of the latter. Additional interest attaches to this process by the further observation of Colonel Waterhouse that development is accompanied by electro-chemical action, in which the current passes in the reverse direction to that observed in the ordinary course of development. In the domain of photographic optics the outlook is en couraging. We have specifications from Dr. Ernst Abb and Dr. Paul Rudolph of an apochromatic objective composed of two uncemented single lenses and a compound correcting lens of considerable focus ; also three forms of unsymmetrical doublets, each possessing special characteristics of its own. The construction of these lenses, which has now been rendered possible for the first time by the introduction of the new kinds of optical glass, has been carried out by Zeiss, of Jena, and they have been favourably reported upon by Dr. Stolze and by Dr. Eder, but they have not at present been introduced com mercially. The primuline printing process of Messrs. Green, Cross, and Bevan, which was brought before the British Association at Leeds, has attracted much attention, and has found useful application in printing on textile fabrics as well as in copying drawings and plans. It is based on the fact that diazotised primuline is decomposed by light, and can then be developed by a phenol or an amine, producing coloured designs on a yellow ground. In Feer’s diazo printing process, which pre ceded the primuline process, similar colours are produced on a pure white ground, without development. The former method requires a reversed positive, the latter an ordinary negative to print from. Both these processes are of special interest, marking as they do a new departure in photographic printing. Mr. M. Carey Lea, further pursuing his experiments with allotropic silver, has produced a well-defined form between it and ordinary silver, of a bright yellow-gold colour, and de scribes the effect of different forms of energy upon it, pro ducing varieties of colours not hitherto obtained. When we look back on the photo-scientific achievements of the past twelve months, I think we must all agree that there has been no lack of progress to record ; but it is a question of, perhaps, still more moment to inquire what advance has been made in the artistic direction. With the numerous exhibitions now held, we have, in spite of the unnecessary restrictions imposed, ample means of forming an opinion of the use we are making of the tools which science places at our disposal. At