Slide rule for calculating haematology constants - gives simultaneous indication of three constants, variation of one automatically giving other two

摘要

The slide rule permits the simultaneous calculation of the three haematological constants from three blood measurements. The rule has three independent movable scales and a supporting base (1). Each scale carries three indexes which are projected on the scales corresponding to the constants. The three operations necessary for calculation of the constants are carried out simultaneously. The variation of a single parameter indicates simultaneously and without any other adjustment the new values of the other two constants affected by the variation.