56 E. E. ROSAIRE AND O. C. LESTER, JR. 
This short profile can also be fitted by a travel-time curve such as 
that approximated by the longer refraction data. For the shorter data, 
the constants are 
b= 4,990 feet per second 
a= 1.25 feet per second per foot. 
The difference in the values of these “‘constants”’ for the two sets of 
data is significant, since it is an indication of the extent to which 
Z in Kilefest 
Nn. 
b=4990 feet per second 
8" 125 feet per second per foot 
2b sT 
(x- 109 “> sinh=— 

34a rice X long 
Fic. 3.—Short refraction data for Vermilion Bay. 
these data can be approximated by a linear increase of velocity with 
depth. 
Partial refraction detail_—The location of the dome by refraction 
fans was recognized as too qualitative for drilling. Therefore, with the 
thought of securing more definite information as to the depth and 
location of the top and flanks, the following detail survey was carried 
out. 
Figure 4 shows the location of these refraction profiles, together 
with the resulting interpretation of the outline. The profile data are 
386 
