STRENGTH TESTING

33i

rejected, because the bursting strain did not increase in exact proportion to
the substance.

The Schopper paper tester (Fig. 143) is a modern adaptation of the old
method of paper testing. Before the introduction of this machine, a strip of

[Coodbrand and Co.

FIG. 144.—TENSILE STRENGTH AND STHETCH TESTING MACHINE
This is the latest and most improved type and is British made

paper of a certain length and breadth was suspended from a clamp; another
clamp was attached to the bottom of the strip and weights were added until
the strip broke. When the Schopper is used, the breaking strain of strips cut
from across the web, and also in the machine direction, is taken, and a short