404 schlink: variance of measuring instruments 



variance loop may fail of closure, divided by the range of the 

 deflection cycle) may be referred to the total range of graduation 

 instead of to particular values of the measured quantity under 

 observation, as a convenient means of arriving at single signifi- 

 cant numbers to be composed in,to a "figure of merit" for an 

 instrument whose characteristics are being determined. It is 

 most desirable to develop definite numerical means of comparison 

 between different instruments or different types of instruments 

 for the same purpose, and the methods just suggested will afford 

 a satisfactory basis for attaining this end, just as the aeronautic 

 engineer's choice of structural material for a given purpose may 

 be based on a single "figure of merit" involving the unit weight, 

 strength, and stiffness determined by laboratory tests. 



