International projectionist (Jan 1941-Dec 1942)

HINTS ON ELECTRIC SHOCK DISABLING electric shocks often act by paralyzing that portion of the brain which controls breathing. In such cases, artificial respiration, as for a drowning person, acts as a restorative. When the path of the current has been such as to paralyze those brain centers that control the heart action, artificial respiration does not restore. However, since only an expert can tell which condition has occurred, artificial respiration should be used and a physician summoned immediately. The amount of current the human body can tolerate is amazingly low, as little as 1.2 milliamperes at 60 cycles producing the sensation of shock when passed through the arms and body. Circuits carrying such low currents normally do not cause shock only because their voltage normally is insufficient to break down the insulation of dry, oily human skin. The body tolerates a.c. and high frequencies better than d.c. and low frequencies. At 60 cycles, 5 milliamperes passing through arms and body have been found to occasion shock to the point of serious distress. At 11,000 cycles, however, the average man can tolerate 30 milliamperes through arms and body before his sensations become distressing. At 100,000 cycles nearly one-half ampere is tolerable. STUDIO NEGOTIATIONS EAST Negotiations between the studio local unions of the I. A. and the producers will be held in New York, according to word emanating from the Coast, which indicates that international representatives will be the chief negotiators of the new deal. It is expected that the local union memberships will be given an opportunity of passing on any deal that is set. S.M.P.E. 50TH ANNIVERSARY MEET IN N. Y., OCT. 20-23 {Continued from page 22) present electrical circuit are described, and the effects of the novel features are shown. An accurate linear density scale is obtained in a single-stage D.C. amplifier, and the sensitivity is sufficient to permit the use of a rugged output meter. A density range of 0 to 3.0 is covered, and the characteristics of the output meter are given. The technics used in prior densitometers in attempting to secure a linear density scale and adequate scale length for good legibility are discussed, and the technic used in the present instrument is compared with them. The performance characteristics of the electrical circuit make it suitable for application to recording instruments. The routine operation is described and the Permanence of calibration is shown. Data are given on the warm-up period and drift, and on the influence of varying line voltage. Operation is entirely by alternating current. Practical performance considerations such as convenience in reading, eye fatigue, etc., FOREST POWER CONVERSION EQUIPMENT RECTIFIERS SUPER MAGNESIUM-COPPER SULPHIDE LD-60 BULB-TYPE LD -40 BULB-TYPE LD-30 BULB-TYPE Meet Every Requirement SUPER MCS . . . using exclusively the P. R. Mallory magnesium -copper sulphide rectifying units. The best in dry disc rectification. Has a newly developed Forest transformer, sure protection against line voltage fluctuations. The Super MCS has —reliable 3-phase fan . . . magnetic switches . . . visual 3-phase line indicator . . . automatic voltage regulator . . . housed in a new sturdily built modernistic case . . . approved by Underwriters Laboratories. LD-60 — Developed to fulfill the requirements for a low-cost arc supply source that can be operated from Low to Simplified High Intensity. Can be operated from 30 to 60 amperes — each rectifier serving one lamp. Where space is limited, the LD-60 is available in the Forest "Twin Type," thus feeding two lamps off the one rectifier. This is the ideal Bulb -Type power conversion equipment. LD-40 — Especially designed to supply DC power to the 1 KW arc-lamps. The amperage range of this rectifier — 30 to 40 plus — guarantees RESERVE POWER when more amperage is required at the arc to brighten up the picture. LD-30— Designed with the exclusive "NO FLASHBACK" transformer feature. This rectifier is for the Low-Intensity arc and, like all other Forest Rectifiers, is more economical to operate than competing products. All Forest Bulb-Type Rectifiers are approved by Underwriters Laboratories, Chicago. OTHER FOREST 'ARC-LIGHT PRODUCTS— UNIVERSAL TRIM AND ONE KW LAMPS— RECTIFYING TUBES— SOUND SCREENS See your "Authorized" FOREST DEALER or send for literature. FOREST MANUFACTURING CORPORATION 200 MT. PLEASANT AVENUE NEWARK, N. J. are reviewed, and figures showing the comparative speed of operation and reading accuracy are given. A REVIEW OF THE QUESTION OF 16-MM EMULSION POSITION fm. H. Offenhauser, Jr. Precision Film Laboratories When a 16-mm sound-film is properly threaded in a 16-mm projector, the emulsion of the film may face the screen (which position is called the "standard" position) or it may face the projector light-source (the "non-standard" emulsion position). In the case of 35-mm film, the standard position for the emulsion of a print is opposite that for 16-mm; in 35-mm, the emulsion faces the light-source of a projector. The anomaly of the 16-mm emulsion position arose from the fact that a large number of the earliest 16-mm commercial sound-films were made by optical reduction from 35-mm S.M.P.E. Fiftieth Anniversary Convention at Hotel Pennsylvania, N. Y. City, Oct. 20-23. At GUST 1941 23