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

AUTOMOBILES AND AIRCRAFT
reaction times and stopping distances at speeds up to 45 m.p.h. was widely
publicized and found its way into many drivers' manuals. A Bureau mem-
ber recalls that the chart continued to appear in at least one of these manuals
as late as the early 1950's, long after high-speed cars had made the data
dangerously
Besides engine research, the Dynamometer Laboratory was also used
to make studies of the durability of tires—of which there were more than a
hundred makes and sizes available. Together with the tire data acquired
during the war, these tests enabled the Bureau to prepare its first Government
master specifications for pneumatic and solid tires and inner tubes.17° The
specifications brought no special joy to the industry.
The center of rubber investigations was in the Industrial building,
where bit and Wormeley were testing rubber goods of all kinds. Until the
rubber section was set up at the Bureau about 1911 there had been almost no
rubber research in this country. Making rubber and rubber products was an
art, with closely guarded trade secrets, and with wide ranges in quality as a
consequence. The exhaustive testing of rubber products at the Bureau con-
stituted some of the first real research in the field, and the successive editions
of the Bureau circular on testing rubber products that first appeared in 1912
became the bible of the industry.17'
By the mid-twenties the Federal Government alone was spending
almost a million dollars a year on tires, and much of the Bureau work in
NBS Annual Report 1925, p. 9, cites a report in preparation on "The maximum pos-
sible deceleration of an automobile." The report seems not to have been published,
but a chart of braking distances, showing speeds up to 20 m.p.h. and possibly prepared
for that report, appears in Standards Yearbook, 1927, plate 36. The brake work was
consolidated in M107, "Safety code for brakes and brake testing" (1930), its chart
on braking distances based on a maximum speed of 45 m.p.h.
Dr. Hobart C. Dickinson, chief of the heat and power division and automobile enthu-
siast, personally directed the many braking studies made by the Bureau. He was most
proud of his paper with C. F. Marvin, Jr., on "What is safe speed?" (J. Soc. Auto.
Eng. 17, 81, 1925) that recommended a "clear course principle" in place of fixed speed
limits for safe driving. Several States adopted its conclusions, he reported in the
paper, as well as its splendid formula, v=5(2as+a2t') —at, in which v represented the
safe speed, a the rate of acceleration, s the clear course ahead, and t the time lag of
the driver.
'70C115 (1921; 2ded., 1925).
171 C38 (1912; 5th ed., 1927). Another aspect of rubber research occurs in a Bureau
letter of 1944 asserting that so great was the difference between Government and indus-
trial salaries for rubber technologists that for 25 years the Bureau had not employed a
single chemist for that work who had had any previous rubber training or work. Letter,
A. T. McPherson to War Manpower Commission, Aug. 3, 1944 (NBS Box 493, ISR).
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