Motography (Jul-Dec 1913)

358 MOTOGRAPHY Vol. X, No. 10 which is driven by the crank, pulls steadily on the film and unwinds it from the upper feed reel. The loose loop prevents the intermittent feed from jerking the film against the inertia and friction of the reel and breaking it off above the gate. When the gate is closed, the film is between the film gate and the framing plate, a spring-actuated device in the gate holding the film against the framing plate in front of the aperture. The friction caused by the springs checks the momentum of the film so that it comes to rest instantly opposite the aperture. The springs rest on the blank margin of the film and the entire device is arranged so that nothing comes into contact with the film in the picture space, thus avoiding the danger of scratches. Owing to the inversion of the lens, the film pictures should be placed so that they are upside down in the aperture, with the emulsion side towards the light. A second loop is now formed at the bottom of the gate, between the gate and the lower take-up sprocket. A spring-controlled idler pulley holds the film firmly on the lower sprocket. After passing over another idler, the film is led to the lower "take-up reel," where it is fastened to the core of the reel by means of a spring clip similar to that on the feed reel. The machine is now ready to be run. As no attempt has been made to place the film pictures in correct relation to the aperture or feeding mechanism, it will be found necessary to secure this adjustment by means of the "framing device" which brings the picture "into frame" or into the correct position on the screen during the time that the shutter is open. Framing is accomplished in different ways on different machines, but is usually accomplished by raising or lowering a lever on the motion head, that raises or lowers the aperture plate. When threading the machine, the greatest of care should be exercised in order to prevent injury to the delicate emulsion surface. Even the smallest abrasions or scratches are glaringly apparent on the screen because of the great magnification. The rapid succession of small scratches and dirt specks, no two of which fall in the same place on the screen, produce what is known as "rain," an expression that describes the appearance of such a film very clearly. Holding the film between the fingers when rewinding, or tightening the film on the reel by pulling at the end of the film with the reel held stationary are the two methods that most commonly result in rainy films. Carbon dust or dust from the interior of the lamp house are also common causes of rain, since the fine particles embed themselves in the soft emulsion. Nothing should touch the emulsion surface, especially while passing through the machine or in rewinding. "First-run" film is soft and is especially susceptible to friction and dirt. The friction of the tension springs in the gate and the rubbing of the guide rollers and sprocket wheels on the margin of the film removes a considerable amount of emulsion especially with first run films. This emulsion dust causes much trouble and should be removed at short intervals to prevent film scratches and mechanical troubles that often arise when the deposit is allowed to accumulate. Deposits that form under the tension springs should be removed after each run to prevent springjumping and slippage. DRY FILM. Before leaving the developing rooms of the film producer) the emulsion is charged with a small amount of emulsion soft and pliable. After a time in service, the glycerine which keeps the gelatine component of the glycerine finally evaporates and the film again becomes harsh and hrittle. The evaporation of the glycerine is, of course, hastened by heat, and for this reason the film should never be stored in a warm place, especially near the ceiling of the operating booth. A considerable amount of moisture should be supplied to keep the film in its best condition. At the present time there are special sheet-metal film containers on the market that are built on the principles of the well-known "humidors" used for the storage of cigars. These devices are circular metal cans, just large enough to receive a reel of film, and are provided with a perforated metal bottom that covers a sponge or other absorbent material. A small amount of water in the sponge supplies the necessary moisture to the film without danger of wetting the emulsion. When the film is dry it may be moistened by unwinding it into a large can, such as a milk or garbage can, that is provided with a false bottom of wire screening. The wire screen is raised two or three inches from the bottom of the can, or high enough to accommodate a shallow pan of water that is to be placed beneath the screen. The cover is now placed on the can, and the film is left in the moisture for a period of an hour to half a day, depending on the condition of the film. If the film is left on the reel, it will require a considerable length of time for the moisture to penetrate to the center of the reel. In any case do not allow the film to become too moist. The manufacturers and film exchanges often 're bate" the film in a three per cent solution of glycerine in water. This process, however, is usually beyond the capabilities of the exhibitor or private film owner, as handling a thousand feet of wet film is no easy matter unless one is equipped with the proper devices. The manufacturer winds the film on large squirrel cage drums and then rotates the film through a glycerine bath contained in a shallow tray. The tray is then removed, and the cage rapidly rotated until the film is perfectly dry. Great care should be taken in handling a wet film for the e"mulsion is very soft, about the consistency of jelly, and is easily damaged by even the slightest contact. Dust adheres firmly to the wet collodion, and when once imbedded is almost impossible to remove. Should a film be wet accidentally, it should be immediately unrolled, and either stretched or wrapped around some cylindrical object such as a barrel or patent clothes-reel. In any case the emulsion side should be turned outwardly so that it will not come into contact with the surface on which it is wound. The unrolling should be performed very carefully to prevent injury to the emulsion. Do not release the tension until the film is bone dry to prevent it from curling and winding. LEADERS. A piece of blank film, or title, of from two to four feet in lenghth, is attached to the beginning of a film to allow for threading the machine. This is known as the "leader." The length of the leader should be greater than the distance from the feed reel to the take-up reel so that the crank may be turned through a couple of revolutions before the body of the film enters the gate. If the leader is too short, there will be equivalent loss of title in threading, making it almost impossible for the audience to determine the name of the play. In attaching a new leader to a film care should be taken to have it in frame with the rest of the film. (To be continued. I