4:90 W. Mason — Neiv Harmonic Analyzer. 



For this reason it is not necessary to draw out the equiva- 

 lent area, but only necessary to place the tracing point of 

 the planimeter in the tracing point of the analyzer, trace 

 the figure, and read the planimeter directly. As the first 

 sin or cosin loops will always be positive in area unless 

 the ordinates themselves are negative, the tracing point 

 of the planimeter should start at the end of this first loop, 

 and follow the upper side around the successive loops back 

 to the starting point. The arrows in fig. 3 illustrate 

 this principle as applied to a derived area from a first 

 sin harmonic analyzer. The sign of the resulting reading 

 will tell whether the harmonic is positive or negative. 



The absolute error measured in inches of result for 

 any harmonic of this machine is given by the formula 



.01 B 



where B is the maximum ordinate of the wave form to be 

 analyzed, and li the wave length of the analyzer. Fig. 4 

 shows a comparison of the errors for the analyzer and for 

 a computation method, using as a basis of comparison a 

 constant ordinate wave form, which is nearly the only 

 form in which errors by a computation method can be 

 directly calculated. The lines on the figure represent 

 conditions of equal accuracy. M in the figure repre- 

 sents the number of ordinates per wave length used in 

 calculating the constants, while li represents the wave 

 lengths of the analyzer used. This figure shows that 

 the analyzer is more accurate, especially for the higher 

 harmonics. 



Lawrence, Kansas. 



