KINET'OSCOPE. An instrument for pro ducing a series of images in such rapid succession that the illusion of actual motion results. The apparatus as usually consists of a pro jecting lantern with an are light as its radiant and a fine projecting lens by which the image is formed. (See :Mime LANTERN.) The pictures of which the images are produced are made on a long celluloid film about one inch in breadth, and of length depending upon the duration of the series of pictures. This film contains a series of photo graphs of a moving. object made at successive intervals, and is rapidly moved in front of the projecting lens by an electric motor or other rotating mechanism. There is also a revolving shutter operated by the saute mechanism which Mines tile tilln, Willa alternately cuts off and allows to pass the light between the film and the projecting lens. The instrument operates by al lowiug a picture on the film to rest for a minute interval in front of the projecting lens, during which time the rays of light are allowed to pass through the opening in the shutter. The next picture on the film, representing a subsequent state in the action, is then brought before the projecting lens in the same manner. The appara tus is adjusted so that between 41) and 50 sue cp•sive exposures of the film occur in a second, and the elect of motion produced on the screen i- wonderfully realisti•,. This is due to the fact that the duration of the impression furnished by light on the retina is about one-fiftieth of a second, and if these impressions follow with suf ficient rapidity the elieet is of continuous motion. This principle has been known for many years, and was first employed ill the stroboscope (q.v.), where a series of slits were cut radially near the circumference of a disk. A moving body was viewed through these slits in the disk as it re volved, and its apparent motion depended upon the relative motion of the mom ing body and the disk. The next important application of this idea was ill the zoetrope, in which a cylindrical box with a series of vertical slits was rapidly rotated about its vertical axis. These slits ex tended from the upper edge of the cylinder half way its height, and within and below was passed a sheet of paper on which were drawn a series of pictures showing an object in successive stages of motion. This instillment. which is illu-trated in the article ITLusioN, mvas for many year, mere ly a popular toy. as it was not possible until the advent of instauta icons photography to depict objects at successive intervals suflieiently aeeurately to enable the instrument to be of praetieal or scientific value. (Mc of the earliest applica
tions of photography to this in strument was when the Al nybridge photographs of moving objects were employed for this purpose. Ilere a intinber of cameras were so placed as to obtain m succession instantaneous photographs of a moving object. From the positives thus ob tained a strip was prepared for the zoetrope, and a life-like representation secured. velopments of this idea and modifications of the instrument were employed, lint it was not until a special form of camera made possible by the use of sensitized films of celluloid was employed that pract hial and satisfactory results were obtained. This was accomplished by Edison in II S93. and the camera employed used a shutter whiell al lowed the light to fall on the film at regularly rceurrino intervals. During these intervals the film remains stationary so that the exposure can be made. and ti then rapidly moved for ward sn that the next exposure is permitted. The action of moving the film and the operation of the shatter is worked automatically, and the process has developed so that rolls of film of great length can be exposed. Time film after its exposure is developed in the usual way. and then a positive .is made which is employed in the proje•thig lantern or apparatus used to view the pictures. In the first form of kinctoseope no attempt was made to project the pictures. but they were examined by the observer through a large magnifying glass illuminated from behind. It is in its application to the projecting lantern, however, that the kinetoscope has found its widest application, and from time to time the methods and apparatus have been vastly improved, with out, however, being radically changed. It is pos sible to photograph almost any subject of interest where sufficient light can be obtained; battles, historic events, and other matters of interest are now reproduced in these moving pictures IT similar instruments, known as the cinemato graph. vitaseope. biograph. etc. The apparatus 11:15 also been employed in scientifie investigations, and an interesting series of photographs showing the propagation, refraction, and reflection of sounfiwaves have been prepared, which when thrown on a screen graphically illustrate the phenomena.