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note that the photographic researches on the eye in general, or the retina in particular, to which we recently referred, are progressing satisfactorily. Dr. Barton takes the lead as regards the histological and physiological aspects of the case, while Captain Abney superintends the chemical and photo graphic work. It was at first sight a little surprising to find that the inside red tints photograph so readily ; but one need only examine blood spectroscopically to under stand the reason of this. We gladly insert Mr. Penny’s letter on the subject of introducing iodide of silver in gelatine emulsion. .His view expressed in December, 1877, that iodide ensures “ greater freedom from veil, giving an image less buried,” seems to have been pretty generally endorsed, as well as the fact that if the salt does not actually increase the sensitive ness of gelatino-bromide, it at any rate obviates “ a mere ghostly image which refused to be intensified.” In a word, Mr. Penny contended that iodide imparted vigour and pluck to the image, and this contention has found favour on many sides. Zutent ntelligence. Patent Granted in United States. 269,830. FRANK B. Clench, of Lockport, N.Y., for “A device for embossing photographs.”—Application filedj 30th October, 1882. No model. Patent Granted in Belgium. 69,630. E. SAUQTET, of Bordeaux, for “ Obtaining relief photo graphic portraits.”—Dated 21st November, 1882. French Patent, 20th May, 1882. Patent Granted in France. 150,096. FERET, of Paris, for “ Oval convex glas for mounts of photographs.”—Dated 13th July, 1882. Class 17. TWELVE ELEMENTARY LESSONS ON SILVER PRINTING. Lesson I. Agreeably to promise, we now commence the series of “Twelve Elementary Lessons on Silver Printing, Toning, Fixing, Washing, Mounting, Finishing, &c., &c.” The intention is to describe each process separately, and in such a manner that young amateurs and beginners generally may be enabled to produce good results. Doubtless, the experienced photographer will not find anything herein written that he is not already acquainted with. Still it may be worth his while to peruse the papers at his leisure. With these few remarks by way of preface, we will proceed with the “printing room.” The locale of the printing room will in the majority of cases be subject to the general convenience of the building and the amount of work required. In large establishments separate apartments are used for each operation, but if only a limited amount of printing is required, one room may be conveniently made to do the duty. It should be situated on or near the ground floor, with easy access to the garden. Having decided upon the room, the next thing is to fit it up in a convenient manner for working; this need not involve a great outlay, and amateurs, at least, will pre fer doing it themselves rather than wait the convenience of the local carpenter. To show the requirement of a printing bench as clearly as posssible, the accompanying sketch is appended, the scale of measurement being one- half inch to the foot. A. Top drawer on the left side for keeping albumenized paper only. B. Drawer for keeping brown paper, tissue, and coloured papers, also papier mineral, cardboard, &c. C. Shelf for sensitizing dish when not in use. D. Shelf for gold toning dish when not.in use. E. Shelf for hyposulphite of soda fixing bath. Note that all dishes should be turned upside down when put away, previously receiving a good wash in clean water. By adopting that plan always, one can be sure of clean dishes. F. Box or cupboard for the reception of silver paper cuttings, waste prints, and defective pieces of sensitized paper; also the filtering papers used for filtering the sensitizing bath, and the blotting-paper used in blotting spots of silver solution on the sheets of sensitized paper. G. Boxes with binged lids for storing the prints after they are removed from the negative; also the sensitized paper before printing, to prevent any darkening action from the light in the room. H. Boxes or pigeon-holes to hold the negatives that have been printed until a convenient opportunity for storing them. I. Window glazed with pale orange glass fitted with extra yellow blind on spring roller for use on very bright days. J. Shelf for storing empty printing frames. K. Shelf for bottles. L. Pigeon-holes for assorted vignetting masks. M. Space left for packing up printing frames at night, or until a convenient opportunity to finish the printing of the negatives in hand. N. Space for oval, dome, or cushion shaped masks; these should, for convenience, be numbered, and after wards kept in their places. O. Drawer for storing dusters, cutting shapes, diamond, &c., &c. P. Spaces for packing the printing frames when not in use. Q. Shelf for graduated measures. R. Shelf with holes cut out to allow the neck of the funnel to pass through, thereby supporting it, and pre venting the chances of the bottle or funnel and its contents being upset. The space from JKLMto the end of the apartment will be found convenient as a drying room for sensitized paper and prints. A couple of stout staples should be driven into the wall opposite K, and two screw eyes or staples driven into the shelf K. A piece of Venetian blind cord and some American clips complete the arrangement. Use one side for prints, and the;other for sensitized paper;