Analysis of information sources in references of the Wikipedia article "Medieval weights and measures" in English language version.
In 1758 the legislature turned attention to this subject; and after some investigations on the comparative lengths of the various standards, ordered a rod to be made of brass, about 38 or 39 inches long, graduated (measured) from the Royal Society's yard: this was marked "Standard Yard, 1758," and was given into the care of the clerk of the House of Commons. For commercial purposes another bar was made, with the yard marked off from the same standard; but it had two upright fixed markers, placed exactly one yard apart, between which any commercial yard measures might be placed, in order to have their accuracy tested: it was graded in feet, one of the feet was graded in inches, and one of the inches in ten parts. This standard yardstick was kept at the Exchequer. In 1760, a copy of Bird's standard, made two years before, was constructed.
