Produced by Chris Curnow, Keith Edkins and the Online Distributed Proofreading Team at http://www.pgdp.net (This file was produced from images generously made available by The Internet Archive)
EACH NUMBER IS ONE UNIT IN A COMPLETE LIBRARY OF MACHINE DESIGN AND SHOP PRACTICE REVISED AND REPUBLISHED FROM MACHINERY
History and Development of Standard Measurements
Copyright, 1910, The Industrial Press, Publishers of MACHINERY.
HISTORY AND DEVELOPMENT OF STANDARD MEASUREMENTS[1]
While every mechanic makes use of the standards of length every day, and uses tools graduated according to accepted standards when performing even the smallest operation in the shop, there are comparatively few who know the history of the development of the standard measurements of length, or are familiar with the methods employed in transferring the measurements from the reference standard to the working standards. We shall therefore here give a short review of the history and development of standard measurements of length, as abstracted from a paper read by Mr. W. A. Viall before the Providence Association of Mechanical Engineers.
By examining the ruins of the ancients it has been found that they had standard measurements, not in the sense in which we are now to consider them, but the ruins show that the buildings were constructed according to some regular unit. In many, if not all cases, the unit seems to be some part of the human body. The "foot," it is thought, first appeared in Greece, and the standard was traditionally said to have been received from the foot of Hercules, and a later tradition has it that Charlemagne established the measurement of his own foot as the standard for his country.
In England, prior to the conquest, the yard measured, according to later investigations, 39.6 inches, but it was reduced by Henry I in 1101, to compare with the measurement of his own arm. In 1324, under Edward II, it was enacted that "the inch shall have length of three barley corns, round and dry, laid end to end; twelve inches shall make one foot, and three feet one yard." While this standard for measurement was the accepted one, scientists were at work on a plan to establish a standard for length that could be recovered if lost, and Huygens, a noted philosopher and scientist of his day, suggested that the pendulum, which beats according to its length, should be used to establish the units of measurement. In 1758 Parliament appointed a commission to investigate and compare the various standards with that furnished by the Royal Society. The commission caused a copy of this standard to be made, marked it "Standard Yard, 1758," and laid it before the House of Commons. In 1742, members of the Royal Society of England and the Royal Academy of Science of Paris agreed to exchange standards, and two bars 42 inches long, with three feet marked off upon them, were sent to Paris, and one of these was returned later with "Toise" marked upon it. In 1760 a yard bar was prepared by Mr. Bird, which was afterwards adopted as a standard, as we shall see later.
