244 PROFESSOR E. G. COKER ON 
TasLe VI. 
Corrected 
: Extensometer Observed Galvanometer 
Time, seconds. Load, pounds, Readings Galvanometer Readings. 
; Readings. k= 0031. 
0 1,000 0 0 0 
—55 
10 2,000 65 1:70 1:73 
— 60 
3,000 115 3°30 
— 52 
35 4,000 167 5°20 5°48 
— 52 
45 5,000 219 6:90 7:38 
— 53 
55 6,000 272 8-60 9°38 
— 58 
63 7,000 330 10°30 11°31 
— 60 
75 8,000 390 12°40 13°84 
— 48 
83 9,000 438 13°90 15°69 
—59 
93 10,000 497 15°50 17:57 
— 60 
103 11,000 557 17:10 19°83 
— 58 
115 12,000 610 18:60 21°91 
— 60 
123 13,000 670 19°10 22°74 
— 57 
132 14,000 727 21:50 25°92 
— 58 
145 15,000 785 23:00 28°17 
— 63 
150 16,000 848 23°90 29°46 
155 17,000 Ae 24:90 30°88 
17,500 
Note.—Distance of scale from galvometer mirror = 6’ 04”. 
that generally there is no very definite yield poimt—the stra gradually increasing 
beyond a certain load, so that the curve showing the relation of stress to strain is well 
rounded, and therefore the yield point is not so well defined. In order to obtain pure 
compression stress without bending, it is necessary to keep the specimen as short as 
possible, and experiments were first made upon compression specimens only long enough 
to accommodate the thermopile, the strain-measuring apparatus being secured to the 
compression plates of the testing machine. This arrangement did not give satisfactory 
results, and after several trials new specimens were prepared, sufficiently long to allow 
of a strain-measuring instrument being applied to them in addition to the thermopile. 
The shortest specimen which could be used under these conditions was 4°5 inches long, 
and, as might be expected, the specimen usually failed by buckling, so that it was not 
