Results of an investigation carried on for the following purposes: (1) To determine the relative life of filaments when operated at low emission (low temperatures) as compared to those operated at high emission values. (2) To determine the nature of the dependence of life upon the initial diameter of the filament. (3) To determine the effect of varying concentrations of water vapor and air upon the life of the filaments. (4) To determine the relative life characteristics of tantalum as compared to tungsten.

Abstract: "This final report discusses the project objectives and the manner in which these were attained in connection with the design and manufacture of the Austin Beta-Gamma Hand and Foot checker (Fig 1). Improvements incorporated to conform the equipment to modern production methods, as well as practical changes to achieve automatic operation and increased stability and to facilitate and simplify maintenance procedures, are covered in detail. The report also includes photographs (Figs. 2 and 3) and a schematic diagram of the final product (Fig. 4)" (p. 1)