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

104 ELECTRICITY, RAILROADS, AND RADIO (1911-16)
materials * * * the largest division of the bureau's work." As the world
of electricity grew Rosa's division grew with it, extending its research in
measurement into electrolysis and electrochemistry, into radio research and
engineering, .and radiology.
To satisfy the industry's need for better electrical standards and bet.
ter measuring instruments, much of the early work of the Bureau was con-
centrated in fundamental electrical measurements. N. Ernest Dorsey of
the electrical division reported some of the results:
The progress that was made in the seven years 1903 to 1910 in
the accuracy of [these] measurements was great. In 1903 it
was generally believed that it was not possible to make absolute
electrical measurements to a higher accuracy than one in one
thousand; by 1910, such measurements had been made with an
accuracy of a few parts in 100,000.
In 1903, manganin resistances were subject to large unexplained
irregular variations; before 1910, these variations had been shown
by [the] Bureau to be caused by the effect of varying humidity
upon the insulation, and sealed coils largely eliminating that effect
had been constructed.
In 1903, the results obtained with the silver coulometer [i.e., volta.
meter] were distressingly variable; by 1910, the major cause of
the variations had been discovered, and several types of coulometers
yielding high reproducibility had been designed.
[Finally,] much improvement had been made in the constancy and
reproducibility of the standard cell.
By the summer of 1910, the modern era of high accuracy in elec-
trical measurements had begun.5
Most of the electrical values that were available to science and in-
dustry in 1903 were far from precise and tentative at best. The first appli-
cation of electricity, to the telegraph, required few quantitative results other
than resistance measurements. But by the 1880's, as electric energy was
applied to light and power, the necessity for accurate measurements of other
electrical quantities, of capacitance, inductance, electromotive force, and cur-
rent, became acute. The Electrial Congress held in Paris in 1881, the first
of many such international conferences, recommended that electric and mag-
netic quantities be measured in terms of absolute units, that is, the same
units used to measure mechanical energy—the centimeter, gram, and second
Hearings * * 1912 (Dec. 2, 1910), p. 267.
'MS, N. Ernest Dorsey, "Some memories of the early days."