.tloaa to addressed to works, All comma:;: \ * ♦ DIRECTIONS FOR USE OF THE KROMSKOP LANTERN London : The Photochromoscope Syndicate, Limited, i 21, Shaftesbury Avenue, W.C. pavement; CLaPHAM 3.W, 1898. DIRECTIONS FOR USE OF THE KROMSKOP LANTERN London : The Photochromoscope Syndicate, Limited, i 21, Shaftesbury Avenue, W.C. 1898. Digitized by the Internet Archive in 2015 https://archive.org/details/directionsforuseOOunse THE LANTERN KROMSKOP. The Lantern Kromskop is an optical device for attaching to an ordinary electric or limelight lantern for the projection of Kromskop color photographs upon a screen, so that they can be seen by a large number of people at once. It is necessary to remove the ordinary optical front in order to employ this attachment, as only a small condensing lens is used, to give parallel rays, which are divided by means of transparent reflectors, and made to pass through the respective colored glasses and images of a specially-mounted Kromogram and separate objectives. Two of the objective carriers are pivoted near the Kromo- gram stage, so that, by means of a lever, they can be swung aside, showing the separate colored images side by side upon the screen, and then, by reversing the motion of the lever, superposing them in exact register. This method of projecting the pictures is very effective, not only as a means of demon- strating the principles of Kromskop color photography, but because the sudden appearance of a perfect color photograph out of a jumble of crude colors affords a fresh surprise and delight with each subject. The construction of the Lantern Kromskop is shown by the diagram, Fig. io, in which g is the small condenser, giving a beam of parallel rays, and h , i are bundles of clear glass which serve to divide the beam into three. The light incident on the first bundle, h , is partly reflected to a silvered mirror from KROMSKOP COLOR PHOTOGRAPHY. Fig. io. which it passes through the red color screen, and the image of the red sensation, at c , to the objective f and thence to the screen. Two-thirds of the light passes through the bundle of glass, h, and this is again divided by a thicker bundle, /, about half of it going to the silvered reflector /, and thence through the blue screen and image of the blue sensation to the objective, d , and thence to the screen. The portion of light which passes through both of the bundles of glass goes through the image of the green sensation, and thence through a green glass and the objective e, to the screen. The objectives are so adjusted that the three axial rays converge to one point upon the screen when the lever system is closed, but separate widely when it is opened, the coned beam of light being kept in the axis of the moving lenses by the THE LANTERN KROMSKOP. 5 operation of the levers q and r , which connect the pivoted objective mounts of the respective silvered mirrors. Although the Lantern Kromskop can be used with any lantern by removing the ordinary optical front, it is especially adapted for use with a “ Popular Science ” lantern devised by the author. This lantern is shown in Fig. n., as used for ordinary science projection, with a sliding front, for carrying three projection systems (such as ordinary objective, microscope or micro-polariscope, and direct- vision spectroscope), and making instantaneous changes by moving it to stops. This multiple front can be lifted off, and the condenser mount and slide carrier swung to one side, leaving a clear platform which sup- ports and centers the Lantern Kromskop, as shown in Fig. 12. Fig. 11. 6 KROMSKOP COLOR PHOTOGRAPHY. Fig. 12. It is then necessary to push the lamp or jet towards the con- denser until the disk on the screen is filled with light. Careful centering and adjustment is necessary to obtain an evenly illuminated disk, which can be separated by the movement of the lever into three colored disks, which are also evenly illumi- nated. The register is adjusted by putting in a slide, closing up the lever so that the objective carriers come together, focussing carefully by sliding the objective barrels in their tube mounts, and then shifting the mounts carefully until the details of the pictures are in perfect register. If the lens mounts will not shift far enough to bring the images into register, the objective barrels can be revolved in the tubes until a position is found which permits of register with less shifting of the mounts. If either one of the images is too large or too small, the size can be made THE LANTERN KROMSICOP. 7 right by a slight readjustment of the focus of that particular objective. Whenever the lenses are taken out to clean, it will probably be found that readjustment is necessary, owing to the imperfect centering of such lenses. The objective for the blue image is shifted by loosening the set screw, and moving by hand. That for the red image has a fine adjustment by screws acting at the top and side. It is, of course, impossible to make satisfactory projections of more than four feet in diameter with the limelight, after dividing it into three portions and filtering through three color screens ; but the results are very effective even in small sizes upon a screen used for much larger projections of ordinary slides. With the electric arc (direct current), excellent results can be obtained up to io feet in diameter, on an opaque screen . A single linen screen is unsuitable. When using the limelight, the lime must be turned so as to prevent pitting, sufficient to shoot the flame forward towards the condensing lens, which is of much shorter focus than the ordinary lantern condensers. Several condensers have been broken by not taking this precaution, but none have yet been broken by the heat of even the most powerful electric arc that can be used in the lantern. For limelight color projections on a larger scale, the author has devised a compact triple lantern with three jets, which can be made to order.