0 
Prof.  Morlev  and  Mr.  Tomlinson  on  Tensile 
to  show  itself  at  about  5-tons  load.  Curve  A  shows  that  the 
material  obeys  the  law  of  proportionality  of  strain  to  stress 
when  the  load  is  applied  quickly,  within  about  the  same  range. 
Curve  C,  to  five  times  the  previous  scale,  and  not  "  sheared 
back/5  shows  the  permanent  set.  From  a  comparison  with 
fig.  1  and  Table  I.  it  appears  then,  that  in  such  a  material  the 
term  u  limit  of  elasticity  "  cannot  be  defined  without  some 
reference  to  time,  unless  it  be  understood  that  an  indefinitely 
long  time  is  to  be  allowed  for  extension  and  contraction  to 
take  place. 
Effects  of  Vibration. 
A  specimen  was  overstrained  in  exactly  the  same  manner 
as  No.  8,  and  then  tested  again.  It  was  then  subjected  to 
a  number  of  sharp  blows  from  a  hammer  both  endwise  and 
transversely,  and  immediately  tested  again.  The  result 
showed  that  the  overstrained  state  was  unaltered  by  the 
vibration,  and  subsequent  tests  showed  that  this  treatment  did 
not  in  any  way  affect  the  rate  of  recovery  from  overstrain. 
Table 
XII.- 
-Specimen  No 
.  15. 
Extensoineter- 
Extensometer-        1 
Load  in 
reading  before 
Permanent 
reading    after 
Tons. 
overstrain. 
Set. 
overstrain. 
Diff. 
Diff. 
j 
01 
200 
200                 ... 
10 
261 
0 
261 
1-5 
295 
34 
0 
297                36 
2-0 
330 
35 
0 
336 
39 
2-5 
365 
35 
0 
376  (?) 
40 
3-0 
400 
35 
0 
411 
35 
3'5 
437 
37 
0 
451 
40 
4-0 
472 
35 
0 
490                39 
4-5 
506 
34 
0  + 
532 
42 
50 
541 
35 
04- 
573 
41 
b'd 
570 
35 
1 
611 
38 
60 
616 
40 
2 
656  (?) 
45 
6-5 
653 
37 
4 
695 
39 
7-0 
691 
38 
9 
738 
43 
7-5 
733 
42 
10 
8-0 
771 
38 
10 
8-5 
S22 
51 
43 
Aluminium-Bronze. 
A  length  of  1^  inch  round  bar  (specimen  No.  2)  was  turned 
down  to  a  diameter  of  I'll 8  for  a  distance  of  10  inches  and 
was  then  tested  and  overstrained  by  a  load  of  37  tons,  which 
