930 ON XmCHEOMATIC PHOTOGRAPHY. [NoV. 28, 



represented as lantez-n-trausparencies prepared from photographs 

 of artistically preserved specimens, and also from the replica of 

 a water-colour drawing of a group of these birds executed by 

 Mr. J. G. Keulemans from living examples. 



Mr. Saville-Kent explained that all tlaese photographs had been 

 taken by him with the Sanger-Shepherd colour-screens, of which 

 he exhibited a set, in conjunction with the Cadett " Lightning 

 Spectrum-plate." These screens represented the three primary 

 spectrum colours, red, green, and blue-violet, as enunciated by the 

 late Prof. Clerk-Maxwell, and a separate negative of the subject 

 had to be taken through each respective screen. The transparent 

 positives prepared from these negatives were stained with tints 

 complementary to those through which they were severally taken. 

 That was — the positive resulting from the red-screen negative was 

 stained blue or minus red ; that from the green screen, red 

 or minus green ; and that produced from the blue-violet screen, 

 yellow or minus blue. Due care being exercised in obtaining the 

 right tint-gradation, and the three stained positives being then 

 superimposed in precise register, an optically perfect presentment 

 or counterfeit of the original subject was mechanically produced. 

 The special method of developing and staining the positives 

 exhibited was, as in the case of the production of suitable colour- 

 screens, associated with the name of Mr. Sanger Shepherd, M'ith 

 Avhom Mr. Saville-Kent had been working in collaboration. 



It was recommended, for the acquirement of perfect registration, 

 that all three of the respecti\e negatives should be taken on a 

 single plate in conjunction with a specially constructed multiple 

 back, of which a sample was exhibited. This, however, was not 

 absolutely necessary. It was competent, in fact, for anyone 

 possessing an ordinary camera to secure correct colour-replicas of 

 desirable objects, using only in conjunction with his instrument 

 the Cadett spectrum-plates and colour-screens referred to. As 

 an illustration of this fact, Mr. Saville-Kent explained that the 

 Peacock's feather, and several other subjects exhibited that evening, 

 had been taken by him with a large-sizad Kodak camera, across 

 the lens of which he had simply slung, with the aid of elastic 

 bands, consecutive sections of 'his multiple-back screen. 



The negatives taken for the production of these lantern-trans- 

 parencies were also available for three-colour printing or process 

 work. In conjunction more especially with such a perfected 

 ma(.-hine as the new^Iy introduced Orloff Colour-printing Press, 

 there was evidently a wide field thrown open for the cheaper 

 reproduction, by printing methods, of Zoological and Botanical sub- 

 jects in their correct natural colours. For lantern demonstration, 

 at any rate, the Sanger-Shepherd process as illustrated by him 

 that evening would, Mr. Saville-Kent anticipated, strongly 

 recommend itself to adoption by the many naturalists who had 

 hitherto employed their camei-as for the delineation in mono- 

 chrome only of the subjects of their studies. In the instances, 

 more especially, of the brilliant but fleeting tints of reptiles, fishes. 



