Measures for Progress: A History of the National Bureau of Standards

TESTING GOVERNMENT MATERIALS 129
section, from an idea supplied by Rosa. For several years Burrows'
permeameter became the standird instrument for determining the magetic
properties of irons and steels, and was used in the preparation of magnetic
standard bars which the Bureau sold as standard samples to manufacturers
of electrical equipment.58
Elated by early results with the permeameter, Burrows became con-
vinced that a close correlation existed between the magnetic and mechanical
properties of materials and went on to develop magnetic test equipment
which he was certain had great promise. The iron and steel industry had
long sought a simple and effective means for detecting flaws produced in
metal during the manufacturing process, as in rifle barrels and prison bars,
in steel beams and track rails, to avoid the slow and costly destruction tests
otherwise necessary.
During the Bureau investigation of railroad materials involved in
derailments and wrecks, Burrows and his group worked to develop a magnetic
method for quick determination of such flaws as the mysterious transverse
fissures found in steel rails. So promising did the first tests appear that
the Bureau reported the method might "possibly become commercially
feasible." In 1918, with special apparatus he constructed incorporating
his permeameter, Burrows left the Bureau to set up a magnetic analysis
firm to do this kind of testing.
Subsequently, other workers at the Bureau found that magnetic and
mechanical properties in metals showed little true correlation, and as a
result the Bureau abandoned its magnetic standard sample work. For almost
a decade the Bureau continued its efforts to develop magnetic tests for proving
metals. Except in the case of soft steel and small metal objects the tests in
most instances were inconclusive. So, to his disappointment, were Burrows'
private efforts, and his firm folded with his death in 1925. Continuing
research at the Bureau indicated that with the permeameter it was "not
possible to realize any units of magnetic quantity in concrete form," and that
it was "only by the greatest care in the selection of test specimens and
manipulation of testing apparatus that an accuracy of 1 percent can be
attained." 60
Although this early work on the magnetic properties of metals—a
phase of Bureau research in the physical constants—led to largely negative
results, some of the most successful work on the determination of physical
constants was soon after to be done in the temperature laboratories of the
NBS C17, "Magnetic testing" (1909).
NBS Annual Report 1915, P. 50; Annual Report 1917, pp. 52—54; Hearings * * *
1920 (Dec. 12, 1918), p.955.
"NBS C17 (4th ed., 1926), p.. 22, and repeated in its sucessors, C415 (1937), and
C456 (1946).