M.H. Mear Fearns viscous calculator IBEX circular slide rule set 1975 England

High quality heavy plastic slide rule called the “Viscous Calcualtor” and build according to the copyright by M/H/ Mears & Co by Fearns Calculators from England (not signed). Made for the IBEX company from Sussex, England. It comes with a letter in English from 1975 (and a translation in German) with a short summery for use. The other instructions are on the slide rule centre. It features various different scales to be read with cursor or from a window. Made specifically for viscous liquids flowing through pipes. The original sleeve is also marked with the IBEX company name. The slide rule is in great condition with minimal signs of use or age. It is fully functioning and the diameter of the slide rule is 15 cm or 6 inches. Also see the pipe flow calculator made to M.H. Mear specs, and the Fearns gas flow calculator. Check the attached video on how to work your vintage man tool: slide rule operation instructions!