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474 1939 SPRING CONVENTION [j. s. M. p. E.
"RCA Aluminate Developers;" J. R. Alburger, RCA Manufacturing Co., Camden, N. J.
A fundamentally new principle in design of photographic developers has been investigated and found to afford many worthwhile characteristics, chief of which is the effective self-replenishing property of the developer solutions. Application of the new principle to developer solution makes it possible to develop about eight times the quantity of film as would be possible under ordinary conditions. The principle may be applied to any developer.
"Push-Pull Class A-B Sound Track;" C. H. Cartwright, Mass. Inst. of Tech., and W. S. Thompson, RCA Manufacturing Company, Inc., Hollywood, Calif.
After an explanation of the term Class A-B and a brief specification of such a recording system, the general requirements for the operation of any Class A-B system are given and illustrated.
Differences between the operation of push-pull photocells and push-pull vacuum tubes are pointed out and explained, and a discussion of the relative advantages of Class A, Class A-B, and Class B push-pull tracks is given.
"A High-Intensity Arc for 16-Mm. Projection;" H. H. Strong, Strong Electric Co., Toledo, Ohio.
A short description of a high-intensity reflector type projection arc lamp and associated rectifier equipment, designed as a light-source for 16-mm. projectors.
"The Status of Lens Making in America;" W. B. Rayton, Bausch & Lomb Optical Mfg. Co., Rochester, N. Y.
When the modern optical industry was born, this country was predominantly agricultural. Its principal industrial developments related to transportation. It was natural, therefore, that Europe should have gained great prestige in the field of optics in the final quarter of the nineteenth century.
With the turn of the century, however, agricultural developments had about reached their limit and industrial activity began to occupy a larger place in American life. Along with others the optical industry felt the incentive to greater activity and the first fifteen years of this century saw a rapid advance in the magnitude of the industry and improvement in the quality of its product.
We were still, however, completely dependent on European sources of supply for our optical glass and for some of the small-demand class of laboratory instruments. Then came the war that not only cut off all aid from Europe but ultimately led Europe to our doors with appeals for optical munitions.
The war only hastened what would have been inevitable anyway, viz., the complete independence of America in optical matters.
The American optical industry has now reached a point where its raw materials (optical glass) and its technical skill recognize no superiors. It can make any practical optical element or instrument for which quantitative specifications can be written.
"Notes on French 16-Mm. Equipment;" D. R. Canady, Canady Sound Appliance Co., Cleveland, Ohio.