Analog visibility computer.
A simple, inexpensive, all solid-state analog computer has been developed for calculating the visual range. Using an input signal from a transmissometer, the computer calculates the visual range by repeatedly solving the Allard and Koshmieder visibility laws. It is accurate to +/-2.0% for visual ranges of between 500 ft (150 m) and 5000 ft (1500 m).
Horner
J L
JL