XX. W. H. WARREN. 
Per cent of elongation in 8” = 1500000 
ultimate strength in Ibs. 
Per cent of reduction of area = 2800000 
ultimate strength in ibs. 
This gives for 28 tons per square inch an elongation of 247 nearly 
and a contraction of area of 44:6%. Tetmaier’s coefficient of 
quality becomes 6°72 inch tons per unit of volume of the test 
piece. 
A recent specification by the Association of American Steel 
Manufacturers (Aug. 9th, 1895) is as follows :— 
Name of Grade. | Tensile Strength. | po" Cont 
Soft Steel ..., 52000 to 62000 25 
Medium Steel 60000 to 70000 22 
The product 62000 by 25 is 1550000, and the product 70000 
by 22 is 1540000. 
If we prefer to use the English ten instead of pounds then the 
above rule becomes — 
Per cent. of elongation in 8” = 670 
strength in tons per sq. inch 
Per cent. of reduction of area = 1250 
strength in tons per sq. inch 
The pound is however, a better unit than the ton, and the latter 
is only introduced in order to render the results more in accord- — 
ance with British practice. 
The following table gives Tetmaiers system of recording the 
various coefficients of strength, elasticity and quality :— 
Tests of Elasticity and Tensile Strength made on 4 round 
specimen of basic ingot iron (fer fondu). 
