The Optical Lantern and Cinematograph Journal (Nov 1904-Oct 1905)

$6 THE OPTICAL LANTERN AND CINEMATOGRAPH JOURNAL. used largely lor hand cameras also yield negatives free from this defect, the film being too thin to cause perceptible refraction of light rays passing through it. Should the negative show halation, and no other be available, it is said that the defect can frequently be greatly reduced by carefully rubbing the surface of the film in the affected parts with a piece of soft linen moistened with alcohol or methylated spirit, and stretched over the tip of the finger. If this operation is carefully performed, a small portion of the film is rubbed away, and increased transparency given to that which remains, but it is obvious that a remedy of this kind should be applied skilfully, and with caution, lest the delicate film should be injured and the negative spoiled. It is desirable that lantern slides should not be printed too rapidly or too close to a powerful source of light, unless the negative is very dense, and it is desired 1o reduce contrast. A gradual exposure at a greater distance from the light source will, in most cases, give a better effect, and will prevent the obliteration of delicate detail and gradations of shadow. The amateur photographer who desires to preserve pleasant mementoes of the scenes of beauty which he has visited, of the wonders of nature, or the triumphs of art and human industry, and to enable others to share in his pleasure and profit, will find an endless source of enjoyment and of pleasant and useful occupation in his leisure hours in the production and display of lantern slides, and may, perhaps, be enabled to bring to light some hidden wonders of creative skill, or to perpetuate, for the benefit of those who are to live after him, the rapidly disappearing examples of the architectural ttiumphs of the past, or the relics of the life of our forefathers, which, in this utilitarian age, are daily giving way to the insatiable and inexorable demands of commerce, or of the manifold and prosaic needs of our daily life. CINEMATOGRAPHY IN COLOURS. According to the Photographische Chronik, Dr. Miethe, of Berlin, has attempted to obtain cinematographic films in colours by the three-colour process, using for this purpose ordinary negative films sensitised with eosine, ethyl red nitrate with a small addition of chinoline red. The lens was worked at an aperture of F. 3 or F. 4, and the filters placed in a rotating sector in front of the film were moved synchronously with the same. The apparatus used for projection was built on the same lines, but the results showed but faint traces of colour and a " ghastly flicker." Dr. Miethe hopes to obtain better results by using a film three times the ordinarywidth, and placing the filters side by side. UNIQUE PICTURES AT THE ST. LOUIS EXHIBITION. Among the German exhibits in the St. Louis Exhibition (according to the Berlin correspondent of the Standard) are four series of colour photographs representing the culture of the vine on the banks of the rivers Rhone and Mosel, German forest cultivation, views of German villages, and the scenery of Lake Garda and the Southern Dalomite Mountains, each series consisting of about fifty pictures. These have been executed, at the request of the German Commissioner for the Exhibition, by Dr. A. Miethe, Professor of Photographic Chemistry in the Charlottenberg Technical High School, and are intended to serve as examples of the advances recently made in Germany in the art of colourphotography. For the projection of these pictures Dr. Miethe employs a special triple lantern of his own design, the illumtnants being three powerful electric lamps, working with a current of from ten to thirty amperes. The condensois consist of a triple system of lenses, each of three parts, and the objectives have various focal lengths, the whole optical system being specially designed to transmit as large a portion of the light as possible, and to suit pictures of every size and description, while provision is made for protecting the slides from injury by the heat of the electric beam. For the proluction of pictures of the highest quality attainable, Dr. Miethe and his assistant, Dr Traube, have devoted special attention to the improvement of the photographic plates, the object in view being to secure their permanence and a high degree of sensitiveness, with as accurate a rendering of colour values as possible. With this view they sought a new class of sensitising materials or pigments ; and in the course of their experiments they made the discovery that the substance known as iso-cyanine possessed the desired properties in a very high degree. By the use of this agent they have succeeded in producing plates which are said to render the colour values in great perfection, and the pictures produced by these means may be expected to mark a very di-tinct advance in this branch of photographic art.