264 
Mr Sears, On the Longitudinal Impact 
until the steady state is reached, and as it begins to take place 
during the first impact, the first series of readings, particularly in 
the case of copper, show greater deviations from the straight line 
law than the second. The figures are as follows : — 
Steel rods, 2" withdrawal 
Length of rods) 
5! 
13! 
21! 
29! 
37! 
(inches) J 
u 8 
8 
Time of impact# 
(10 -4 secs.) J 
1-501 
2-319 
3-089 
3-868* 
4-675 
Copper rods, 
2" withdrawal 
Length of rods (inches)... 
5f 
13# 
21# 
37# 
rr,. r . , (Initial 
lime of impact 1 
1-845 
2-993 
4-064 
6-193 
(10- 4 secs.) ] Steady 
1-617 
2-721 
3-817 
6-041 
(There were no copper rods 29# " long, owing to lack of material 
when they were made.) 
Aluminium rods, 2" withdrawal 
Length of rods (inches)... 
6 
16 
26 
36 
rr,. n . , (Initial 
lime of impact ) 
1-611 
2-602 
? 3-621 
4-619 
(10~ 4 secs.) j gteady 
1-349 
2-272 1 
3-354 
4-359 
The values of the wave-velocities got by plotting these figures 
are as follows : — 
Steel ... ... ... ... 1 6,820 ft. per sec. 
Copper ... ... ... ... 12,060 ft. per sec. 
Aluminium ... ... ... 16,620 ft. per sec. 
* This pair of rods overstrained. The ends were accordingly re-turned and 
polished and the experiment repeated. The figure given here represents the mean 
of the two initial readings. In the other cases no overstraining occurred, and the 
figure given is the mean of five readings. 
f This pair of rods overstrained to a greater extent than any of the others, the 
difference being easily perceptible on observing the ends as above described. 
