An 8 cm by 24 cm, cardboard, slide rule distributed by Radiation Counter Laboratories (RCL) that allows one to calculate a number of functions based on half-life, dead-time of counters, absorption material, standard deviation, etc. It will also generate an estimate of the beta particle energies for a specific range. The instruction manual was copyrighted by RCL in 1949. The listed sale price at that time was $1.00.
