Early Standards Of Length. To meet the earliest need of units of measure, it was natural to adopt the means nearest at hand, and common consent, no doubt, brought into use the pace, the forearm, or cubit, the foot, the hand, the nail, etc. These were certainly convenient enough, for wherever he might go, every individual carried his units of measure with him. Variations in their length, however, were inevitable, and many attempts were made to reduce them to a standard. An old English statute, the substance of which has descended to American arithmetics of modern date, enacts "that three barleycorns, round and dry, make an inch, twelve inches make a foot, three feet a yard, etc.; and there seems to be no doubt that this mode of obtaining a standard was actually resorted to. But setting aside the objection due to the varying size of the individual grains, - unless the average of a large number be taken, - it is so difficult to know how much of the sharp end of a grain of barley must be removed to make it 'round,' that the definition is not of much value. Nevertheless, in spite of numerous attempts at legislation on the subject, this, down to the year 1824, was the only process by which the standard yard of this country [England] could, if lost, be legally recovered."

Fig. 27.

Previous to the institution of a national standard of length in Great Britain, influential men and prominent societies provided themselves with so-called standards, which were accepted and used in different localities. By comparison with many of these, the present standard of length was made, and its length defined by law as the British standard yard. From this, about fifty copies have been made. Two of these copies were in 1855 sent to the United States, and have since been in the keeping of the Coast Survey. They are described as follows: 15. "Each standard of length is a solid bar 38 inches long and 1 inch square, in transverse section. One inch from each extremity a cylindrical well, one-half inch in diameter, is sunk one-half inch below the surface. At the bottom of the wells, in each bar, is a gold pin about 0.1 inch in diameter, upon which are drawn three transversal and two longitudinal lines. The wells are protected by metal caps. The length of one English yard at a specified temperature is defined by the distance from the middle transversal line in one well to the middle transversal line in the other, using the parts of those lines which are midway between the longitudinal lines." 2