STANDARD VOLUME INDICATOR AND REFERENCE LEVEL 125 



the two scales. This arrangement permits the installation of the 

 instrument which features the scale that is most important to the user, 

 while retaining the alternate scale for correlation purposes. 



The new scale retains the simplicity and the general color scheme of 

 the former Fig. 12 scale. The main division markings and the asso- 

 ciated numerals are, in each case, in black. The secondary data are 



Fig. 16 — New volume indicator — A scale. 



smaller (and in one case are in red) and therefore less conspicuous 

 than the others. All irrelevant markings have been omitted from 

 the scale. 



The color of the scale card, which is a rich cream, seems to be a 

 satisfactory compromise between high contrast and reduced eye- 

 strain and fatigue. This choice is based upon the preference of a large 

 group of skilled observers and upon the reports of certain societies for 

 the improvement of vision. The use of matte finished instrument 



