Fisher Control Valve Sizing Rule

[side 1]
Fisher Control Valve Sizing Rule
Fisher Copyright 1954
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[side 2]
Fisher Governor Company, Marshalltown, Iowa, USA.

One of two specialist slide rules donated by Mr. John Bradley, formerly of Fisher Control Valves. The rule comes in a leather case marked Pickett, which is the manufacturer Pickett & Eckel Inc. It was used in the period 1950-1980 in the design and sizing of Oil Control Valves.
Each photo shows both sides of the elements of this object.This Slide Rule is in excellent condition with its original box and data sheet.