ENLARGEMENTS.
The instructions here given apply also to the production of enlargements (see also section dealing with that sub ject), the only difference being in the method of exposure. Very large pic tures have to be dealt with in a special manner. The panoramic view of the Bay of Naples, by the Rotary Photographic Co., is claimed to be the largest photo graph in the world, and is exceptionally interesting. It was produced by making six whale-plate negatives from the same point, rotating the camera on the optical centre of the lens, and just allowing a slight overlap of subject to ensure meter, and the dishes consisted of huge vats capable of holding about •50 gal. of solution. These were arranged to run on rails 70 ft. in length. Fig. 33S shows the accurate register. These negatives were enlarged on a continuous band of bromide paper, 36 ft. by 5 ft. Fig. 337 illustrates the ingenious method of development adopted. The wheel measured about 12 ft. in din preparations for development, which was arranged to take place in the night, as, of course, the construction of a dark-room of sufficient size was out of the question. Fig.
339 shows the picture being transferred to the washing trough, a wooden structure capable of holding :3,000 gal., and measur ing 4S ft. by 6 ft. by 20 in. The sensitive paper, with an opaque outer covering, was carefully attached to the wheel, and the developing vat run into position, the pro tective covering being removed as the paper was allowed to go into the developer. Local development was employed on parts which appeared too light or too dark, and finally the huge enlargement was sprayed with a weak solution of acetic acid applied with a hose to stop development. Another vat with acetic acid solution was then run print may he produced by snlphocyanide of ammonium and gold, on one which is brown from prolonged development. Take 20 grs. of ammonium suiphocyanide, and dissolve in 1 oz. of water. Mix 2 grains of gold trichloride with 1 oz. of water. The gold solution should be added to the other in small portions, well mixing. The print is immersed in this until of the desired colour.