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IOWA ACADEMY OF SCIENCE Vol. XXIV, 1917 
a displacement of 90°. One observer with the “closed” binaurals 
had : one curve with no breaks, one with possibly a slight break, 
and four with decided breaks. This same observer with the 
“open” binaurals had four, with a decided break in the curve. 
For another observer the breaks were not so marked, that is, the 
difference in slope was not so great. For the “closed” binaurals 
(l) 
.5 1.0 1.5 
Figure 27 
out of six curves two were without breaks, the rest had one 
each. For the “open” binaurals he had out of three curves 
two straight ones and one with a very slight break in it. 
Why it is that for the same person, sometimes the curve is 
perfectly straight up to 90° while at other times it has a de- 
