[Bovey ] 
A NEW EXTENSOMETER 
Le 
Table showing mean strain in 7.1-in. X 3.33-in. cast iron beam 
under three different systems of loading. 
Compressive strains 
Tensile 
Extensometers 1.6-in. c. to c. 
«6 
+ 
The strains are, in each case, the means of jive observations. 
TOTAL STRAINS AT DIFFERENT POSITIONS OF EXTENSOMETERS. 
IN MILLIONTHS OF AN INCH. 
Load JE 
in lbs. 
000 000000 
S 800 + 234 
= 
2 1600 + 465 
5 2400 + 688 
‘es 
ra) (0) 2 
É 320 4. 87 
4000 + 1075 
a 000 000000 
& 1200 + 249 
Bs 2400 + 505 
BH 
23 3600 + 710 
n oO 
É 4800 + 968 
À 6000 + 1220 
À 000 000000 
[= 
& 2400 + 27 
aos 4800 + 502 
ÊE 
8£ 7200 + 743 
a 
5 9600 + 984 
Gi 12000 + 1232 
Diagrams 1 to 3 have been prepared from 
mire 
000000 
+ + + + + 
000000 
126 
259 
III. 
000000 
2 
000 
003 
seem to justify the following inferences:— 
(1) The first set of readings for each of the tests indicates a 
generally greater deviation from the mean than the subsequent readings. 
This is particularly noticeable in the case where the loads are 20-ins. 
from the centre, when the neutral surface moves apparently towards 
the tension side. 
HV 
000000 
469 
597 
V. 
000000 
=| PPA 
! 
_ 
bo 
=" 
© 
— 947 
— 1194 
the above results, and 
(2) The curves for the load at the centre show less variation in 
the position of the neutral surface than when the loads are concentrated 
at equidistant points. The axis is precisely at the mid depth of the 
