The Curveasy Charts
The Curveasy chart set was copyrighted in 1950 by Earl H Needham [the producer of the Trig-Easy charts, see earlier post] and sold by the Eugene Dietzgen Co. My set, which I believe to be complete, consists of
1. A wallet
2. A 64 page manual containing instructions, worked examples, illustrations and tables.
3. Two 97mm x 85mm charts
American machinist: Volume 102, Issues 5-8 1958.
The Electriaid Charts
The Electriaid chart set was copyrighted in 1948 by Earl H Needham [the producer of the Trig-Easy and Curveasy charts] and sold by the Eugene Dietzgen Co.
The set was described as being designed as reference aids for electrical students and engineers. A complete set appears to consist of four double-sided, pocket size (3 7/8″ by 3 1/2″) dial charts and two cards containing over 120 equations, conversion tables, and constants.
I do not have these charts and the photographs below are not mine.