64 L. D. LEET AND W. M. EWING 
VII. Wrsterty RESULTS 
The time-distance graph for Westerly is shown in Fig. 5. The velocity 
for longitudinal waves obtained from these data was 16,400 +120 ft./sec. or 
5.00 +0.04 km/sec. 


TIME tN 2 SECONDS 




TIME- DISTANCE CURVE 
ROCKPORT "GRAN ial = 
DISTANCE IN FEET 
300) 
Fig. 5. 

IME IN SECONDS 
T 
» [72-4-4 
(igedeq 

VILL. AVERAGE LONGITUDINAL VELOCITY 
The weighted average of these three longitudinal velocities is 16,530 
+90 ft./sec. or 5.04+0.03 km/sec. 
The close agreement in velocity found here for three well-separated and 
different types of granite indicates that minor fluctuations in composition 
do not seriously affect the velocity. 
IX. ANALYSES 
Chemical 
The following analyses of specimens from the regions investigated were 
made by Mr. Forest A. Gonyer, chemist of the Harvard Department of 
Mineralogy. 
Mineralogical 
The following mineralogical analyses were made by Mr. Chalmer J.Roy, 
Assistant in the Department of Geology, who was a member of the party 
throughout the investigation. 
The Westerly analyses were made from thin sections. The Rockport and 
Quincy determinations were made by gravity separation methods from initial 
samples of 1000 grams. 
208 
