Photo-Sculpture Pigeon Post
light than ordinary plates. The rapidity of the plate is not a subject of much consequence,, as equally good results have been obtained by eminent workers on both slow and rapid makes. A convenient photomicrographic device for low powers, and also available for sketching, is that of Edinger, recently described in The Amateur Photographer. The sketch (fig. 106) shows the device as used with the camera. The flame of the lamp is, of course, screened by an opaque outer chimney, having an aper-ture corresponding to the condensing lens in the horizontal tube ; a reflector at the other end of the tube throws the light down on the object, which is on an independent stage, and the micro-scopic objective is mounted in the camera. When an image is to be projected on the base-board for sketching, the lower arm carries the objective.
• Stereoscopic Photo-Micrography. There is an old and very satisfactory method by placing the slide or object in a tilting frame attached to the stage of the microscope. The frame with the object being tilted to one side to the proper angle, a photo-graph is taken ; the frame is then tilted to an equal amount in the opposite direction, and another photograph is taken. Prints from the negatives are then mounted in the usual way, to form a stereoscopic slide.
Photo-Sculpture. See Sculpture, Photographic.
Photo-tint Process. A collotype method worked by Messrs. B. J. Edwards & Co. in the mid-seventies. An example is given as the frontispiece to Tissandier's " History and Handbook of Photography," translated by J. Thomson, London, 1876. Sampson Low & Co.
Phototype. A mechanical printing process in which a gelatine film itself is used to print from. (See Collotype.)
Phototype Blocks. See Fish Glue Process and Chemi-graphy.
Pigeon Post. An ingenious application of micro-photography, carried out by M. Dagron, when Paris was besieged by the Germans. Messages to those outside were set up in type and reduced by photography so considerably, that a bundle of films weighing 15 grs., and forming the load for a pigeon, contained over 80,000 words. On the safe arrival of a pigeon at its desti-nation, the messages were transcribed and forwarded. Those