IN BEAMS SUBJECTED TO TEANSVEESE STEAIN. 
481 
The same beam with the bearing distance increased to 84 inches. 
Beam 
without 
weight. 
Differ- 
ence. 
Weight 
applied at 
centre, 
8000 lbs. 
Differ- 
ence. 
Weight 
taken oiF. 
Per- 
manent 
set. 
Beam 
without 
weight. 
Differ- 
ence. 
Weight 
applied at 
centre, 
8000 lbs. 
Differ- 
ence. 
Weight 
taken off. 
Per- 
manent 
set. 
Microm. 
Microm. 
Microm. 
Microm. 
Microm. 
Microm. 
readings. 
1757 
+ 36 
readings. 
1793 
-36 
readings. 
1757 
readings. 
1753 
—36 
readings. 
1717 
+ 35 
readings. 
1752 
— 1 
1787 
+ 17 
1804 
-18 
1786 
-1 
1786 
—23 
1763 
+ 21 
1784 
-2 
1682 
+ 4 
1686 
- 3 
1683 
+ 1 
1683 
- 9 
1674 
+ 7 
1681 
-2 
1812 
— 11 
1801 
+ 10 
1811 
— 1 
1813 
+ 6 
1819 
— 5 
1814 
+ 1 
1743 
—26 
1717 
+ 24 
1741 
— 2 
1739 
+ 24 
1763 
-21 
1742 
+ 3 
1779 
-39 
1740 
+ 40 
1780 
+ 1 
1779 
+ 35 
1814 
-38 
1776 
— 3 
Experiment for Determination of Neutral Axis. 
Wrought Iron Beam (hammered iron). 
Depth 7’25 inches. 
Breadth 1‘76 inch. 
Length of bearing .... 88 inches. 
Beam 
without 
weight. 
Difference. 
Weight 
applied at 
centre of 
beam, 
10,266 lbs. 
Difference. 
Weight 
applied at 
centre of 
beam, 
19,226 lbs. 
Difference. 
Weight 
applied at 
centre of 
beam, 
23,706 lbs. 
Difference. 
Weight 
taken off. 
Permanent 
set. 
Micrometer 
readings. 
1560 
+ 24 
Micrometer 
readings. 
1584 
+ 21 
Micrometer 
readings. 
1605 
+ 18 
Micrometer 
readings. 
*1623 
-61 
Micrometer 
readings. 
1562 
+ 2 
1599 
+ 18 
1617 
+ 10 
1627 
+ 8 
1635 
—34 
1601 
+ 2 
1624 
+ 7 
1631 
+ 4 
1635 
— 2 
1633 
— 15 
1618 
- 6 
1643 
— 5 
1638 
- 6 
1632 
- 8 
1624 
+ 6 
1630 
— 13 
1456 
-12 
1444 
-14 
1430 
— 20 
1410 
+ 27 
1437 
-19 
1401 
-22 
1379 
—25 
1354 
-29 
1325 
+ 52 
1377 
—24 
xAlthough the extensions and compressions are only about half that of cast iron, and 
consequently the liability to error in the measm’ements is increased in proportion, yet the 
experiments point out that the position of the neutral axis in wrought iron, like that of 
cast, is at the centre of gravity of the section, and that the action is the same in both 
materials, excepting as to the amount of the extensions and compressions with a given 
strain. 
IW 
The formula 2(^f-\-(p^)dd'^= — , given in the former part of the paper for cast iron, 
will therefore apply to wrought iron also. 
The relative values of y and ^ are not so readily ascertained in wrought iron, because 
the material yields by bending and not by fracture. And another point requires con- 
sideration, namely, that the ultimate compressive strain which wrought iron is capable 
* Previous to these measurements being taken, a weight of 14,093 lbs. was applied on the end, equal to 
28,186 lbs. on the centre of the beam, but was reduced to 23,706 lbs. in the centre. The elasticity of the 
beam had, however, been overcome, as shown by the permanent set and by subsequent experiments on the 
same beam. 
3 E 
MDCCCLVII. 
