W. S. _The lens is certainly very good; you should practise to obtain an accurate focus on the ground glass. An experienced hand will often demonstrate how much the actual sharpness of a picture depends upon nice adjustment of the focus; for though the picture looks pretty, it is not sharp in detail._ PHOTO. _We hope shortly to be enabled to report upon the new paper manufacturing by Mr. Saunders for photographic purposes._ "NOTES AND QUERIES" _is published at noon on Friday, so that the Country Booksellers may receive Copies in that night's parcels, and deliver them to their Subscribers on the Saturday_. * * * * * PHOTOGRAPHIC CAMERAS. OTTEWILL AND MORGAN'S Manufactory, 24. & 25. Charlotte Terrace, Caledonian Road, Islington. OTTEWILL's Registered Double Body Folding Camera, adapted for Landscapes or Portraits, may be had of A. ROSS, Featherstone Buildings, Holborn; the Photographic Institution, Bond Street; and at the Manufactory as above, where every description of Cameras, Slides, and Tripods may be had. The Trade supplied. * * * * * PHOTOGRAPHIC APPARATUS.--MR. JOHN J. GRIFFIN has now ready an entirely NEW CATALOGUE OF PHOTOGRAPHIC APPARATUS AND CHEMICALS at Reduced Prices; embracing an account of every article required for the processes on Silver, Paper, and Glass, with estimates of the cost of complete sets for Home Use and for Travellers. Postage Fourpence. JOHN J. GRIFFIN, F.C.S., Chemist and Optician, 10. Finsbury Square, London. * * * * * PHOTOGRAPHY.--HORNE & CO'S Iodized Collodion, for obtaining Instantaneous Views, and Portraits in from three to thirty seconds according to light. Portraits obtained by the above, for delicacy of detail rival the choicest Daguerreotypes, specimens of which may be seen at their Establishment. Also every description of Apparatus, Chemicals, &c. &c., used in this beautiful Art.--123. & 121. Newgate Street. * * * * * IMPROVEMENT IN COLLODION.--J. B. HOCKIN & CO., Chemists, 289. Strand, have, by an improved mode of Iodizing, succeeded in producing a Collodion equal, they may say superior, in sensitiveness and density of Negative, to any other hitherto published; without diminishing the keeping properties and appreciation of half-tint for which their manufacture has been esteemed. Apparatus, pure Chemicals, and all the requirements for the practice of Photography. Instruction in the Art. THE COLLODION AND POSITIVE PAPER PROCESS. By. J. B. HOCKIN. Price 1s., per Post, 1s. 2d. * * * * *