The motion picture projectionist (Oct 1928-Oct 1929)

April, 1929 The Motion Picture Projectionist 37 Hints on Battery Care IX operating storage batteries, a few points should be understood as to their care. If these few simple directions are followed, long life will he obtained from the battery and batten troubles will he eliminated. The principal points to he kept in mind are as follows: Keep I he Outside of the Battery Clean and Dr> 1 )ampness and dirt permit the electric current to leak away and leakage may cause noise in the amplifiers. In time, wood battery cases will become rotted and the terminals become corroded. Keep the vent plugs, (see figure 6), in place at all times, except when taking a specific gravity reading or when adding water. If acid is spilled or the battery is damp with acid, apply a small amount of a dilute solution of ammonia or baking soda and water, which will neutralize the acid. Then rinse the battery with water, and dry. Do not allow this ammonia or soda solution to get into the battery cells. Keep Terminals Clean and Tight Sometimes a deposit will form on the terminals of the battery. Remove this with weak ammonia or soda solution and scrape the metal clean. Then cover the terminals with a thin coating" of vaseline to prevent further corrosion. Keep all terminals tight, as a single poor connection may result in much amplifier noise. Add Water to the Cells Regularly The water in many cities is satisfactory for adding to the hatter)". However, use distilled water if there is anv doubt. Never allow the surface of the electrolyte to drop below the tops of the plates. Add water when needed until the level of the electrolyte in rubber jar cells is just below the bottom of the filling" tube. In glass jar cells, fill to the water line. To let the electrolyte fall below the tops of the plates allows just that much of the plates to dry out. That part of the plates which has been allowed to become dry becomes inactive in the chemical reaction. In other words, the capacity of the battery will he reduced in proportion to the amount of plate surface which has been allowed to dry out. It can be converted into active plate surface again onlythrough elaborate treatment. Three is also a permanent deterioration of that part of the plates which has dried out. Add water just before charging. This allows the water to mix thoroughly with the electrolyte during the charge, as there is always some bubbling or gasing during charge. Do not add water just before or during use in a show. Keep Terminals Clean and Tight It is very important that all open flames he kept away from the battery, particularly while charging. Use an electric flash light. Hydrogen gas is given off by the battery in charging and certain mixtures of hydrogen gas and air are highly explosive. Make Readings Carefully In taking specific gravity readings with a hydrometer syringe there are a few points to keep in mind. Draw into the syringe sufficient electrolyte to float the hvdrometer in the syringe clear of the from the audience is as nothing" compared with the convenience of the exchange inspectors. And this sample is only one of the many I have encountered lately. In one instance I found no less than 55 splices in one reel, all of which had to be remade before projecting. I complained of this print to the manager. and he immediately got in touch with the exchange. Prints from that exchange have been uniformly good since that time — which ought to suggest similar courses of action to other projectionists. Small Houses at Disadvantage The fellow in the large house may not he seriously affected by such work, since they usually receive new prints, and their working schedules allow ample time for any corrections. However, the fellow in the small house never sees his show until 30 minutes before running time (sometimes even less), yet good projection is just as important to Mr. Little Theatre Owner as to the "big shots." And if anyone thinks the former does not care about projection, one is mistaken. Let the exchanges first correct their own employes, and then, if the trouble still persists, look to the projectionist. Why we projectionists, as a craft, take such nonsense as the wholesale accusations by exchanges that we alone art' responsible For had film is beyond me. If the responsibility. for good film were put up to us properly, action by the craft as a whole would he necessary. And this would be a good thing. Your plan to supply the craft with constant education is commendable, as is your idea that the matter should be dealt with properly by the craft as a whole. Education is the one thing we can never have too much of, and I am sure it will never lire the man who is working honestly day byday to improve himself and his craft. Deficient Equipment In closing. I wish to say a few words about this matter of film speed. It is obvious that if the production was originally photographed at a given rate of speed, it must be projected at the same speed, if the actors are to appear natural and if the ideas of the director are to be carried out. It is when a reasonable rate of speed — say 90 ft. a minute — is exceeded in projecting that the speed may really be termed "excessive." Projection speed is not our greatest concern just at the moment, ft would he better if we would agitate for the chance to run our shows with equipment that was up-todate and capable of giving a good show. The boys are capable; but we certainly cannot he expected to give the proper results when we are asked to operate equipment that is old or faulty. soft rubber stopper in the bottom, but do not draw in enough electrolyte to allow the stem of the hydrometer to touch the Hip of the syringe. Release all pressure on the rubber bulb when reading. If the level of the electrolyte is too low to obtain sufficient electrolyte to float the hydrometer bulb, add water to the battery, but do not take a specific gravity reading until this water has been mixed by charging. Avoid Over-Discharging It was explained that on discharge, lead sulphate was formed m both positive and negative plates. Lead sulphate occupies more volume than either the lead peroxide of the charged positive plates or the pure lead of the negative plates. Provision has been made in the plates for taking care of a certain amount of this expansion. 1 1. •however, the discharge is carried. too far, the plates will he permanently injured and their life shortened. Do Not Let a Battery Remain in Discharged Condition Lead sulphate, which is formed in both plates on discharge, hardens in the plates if allowed to stand in this condition for any length of time. If this lead sulphate becomes bard, it is difficult to drive the acid out of the plates and back into the electrolyte again by charging. This condition is what is commonly known as "Sulphated Battery." Excessive Charging Rate If the charging current is maintained too high, especially toward the end of the charge, there will be overheating, which may char the separators and injure the plates. Do Not Over-Charge Do not over-charge repeatedly. Continuing the charge, after a hydrometer reading shows that the battery is fully charged, will weaken the plate structure and in time will result in cracked positive plates. This results in decreased capacity and possible internal trouble from short circuit. Dworsky junior Cleaner "i'he Dworsky Film Machine Corp., 61 Sixth St., Long Island City, N. Y., has introduced a new Dworsky film cleaning" machine which is known as the Junior Theatre Cleaner. This new machine does exactly the same work as the larger cleaner, the only difference being that its footage capacity is less. Like all Dworsky film cleaning machines this new product is motor driven, which insures maximum efficiency in cleaning prints. A feature of the Junior model is the double-breaking attachment which permits control of the machine by either the band or the knee. Don't Scrape Emulsion Emulsion should not be scraped off the sound gate. Scraping scratches the polished surface which easily again becomes coated with emulsion. The proper way to remove emulsion from tin gate is to use a dampened cloth, which does not harm the surface.