The Optical Magic Lantern Journal (November 1896)

London a comparatively cheap slide of the grand canal in Venice to fill up a gap in my Italian set. When it arrived I found that the artist, having evidently more red paint than information, had coloured the largest gondola in the picture a brilliant scarlet. Now I knew that any person in my audience who had been in Venice would know that by Act of Parliament all gondolas are coloured a sombre black and appear to the visitor like so many hearses! (To be continued.) oy ee Animated Photographs. By G. R. BAKER. lantern world has been interested in the results obtained by taking a objects in rapid succession for ultimate projection on a screen, but the climax has been reached during the past twelve months, since the results of the labours of Mr. Birt Acres, Messrs. Lumiere, and Mr. Paul have been before the public. The | that has culminated in the cinematographe, introduction of Edison's kinetoscope and the wonderful effect produced for individual observation was only a preliminary to some similar effect capable of being seen by hundreds of | persons at one time, and the designing and construction of an apparatus for such a purpose followed as a natural consequence. The difficulties in new apparatus is generally great, especially if mechanical as well as optical problems have to be solved ; but in this instance, with the continuous roll of photographic records an accomplished fact, engineering skill and the optician’s aid managed the remainder. The films of the kinetoscope, although sharp and well defined and satisfactory for visual observation, are not, as usually supplied, suitable for projection, for they are too dense and consequently do not allow sufficient light to pass through to appear bright on the screen. With the films specially printed so as to ensure transparency, the results are much superior. When one first sets about constructing an apparatus for the projection of kinetic photographs, the plan of a revolving wheel or disc with an aperture in it as used in the kinetoscope is naturally tried, but it is soon found that little or no light is the result on the screen. Hence some mechanism and shutter must be employed that will permit a momentary stopping of the film and an exposure of a definite portion of the same, so that the whole or nearly the iy Y ‘NOR many years past the optical i series of photographs of living | The Optical Magic Lantern Journal and Photographic Enlarger. | | tures.” whole of the light from the luminant passes through and is projected on the screen. To do this without vibration and the minimum of noise is the task set the instrument makers. The light can be managed all right, for almost any power is available with the electric light, but provision has to be made for protecting the films from injury by the heat rays, and this is done by a water trough. The front lens has to be of very short focus to get the necessary enlargement of the little film pictures so as to appear a reasonable size in a moderate-sized ; hall or room, but if the distance is great a longer focus can be used and proportionately more light obtained. The focus of the objectives usually employed is from two to four inches equivalent focus. In searching the Patent Office records, one finds that Wordsworth ODoristhorpe and William Carr Crofts, both of London, made application in August, 1889, for a patent which was duly accepted in November, 1890, for ‘Improvements in the production and representation of instantaneous photographic picThe following abridged description will ' show that these inventors were on the track animatograph, and a dozen other graphs :— ‘The pictures are produced upon a sensitive film or surface carried by a long roll of paper or other material. The rollis continuously unwound from one drum and wound on to another drum. | A screen is provided between the lens and the | exposed sensitive surface. This screen travels out of the way to permit the image to fall on the sensitive surface, and covers the lens again as soon as the exposure is complete. The | operation takes place with regularity, and usually with great rapidity, so that several pictures are taken in each second. A band is provided with two perforations to make these exposures. Positive pictures are taken from the strip after development, and a similar band of positives is produced and rendered transparent by application of vaseline or oil or other suitable process. The data started from is that the eye receives an instantaneous impression and retains it for one-seventh of asecond. The regular intervals should be 8 to 6 per second, and for projection the blank interval one-sixteenth to one-twelfth per second.” In the above the main prirciples are those that have been so successfully brought to an issue by Lumiere, Birt Acres, Paul, Friese Greene, and others; the details of shutters, spocket wheels, intermittent action, star wheels, being modified in each invention so that the designer or constructor can claim an improvement,