Arthur S. C. Wurtele

“ Having shown in the preceding pages that in the point of view of scientific accuracy the yard, mètre, and toise standards are on a common level, and that in the matter of comparisons there is no extreme accuracy, I will now refer to the proposed change of our standard from the yard to the mètre.
Theoretically the mètre is the 10,000,000th part of the earth’s quadrant, and the yard the 36/39·13929th part of a seconds pendulum at London. Practically, neither the mètre nor yard could be recovered with exactness from their natural basis. ”

“ It appears to me that comparisons should be made of double yards and mètres with the old French toise, as the limit of exactness would be thereby doubled.
Another great defect in statements of relative values is the omission of necessary facts—the material of which the bars or standards are made, the temperature at which comparison was made, and the standard temperatures used as to the final reduction, with the coefficient of expansion adopted. ”

“ I have endeavored to indicate what may be the cause of this confusion by giving the figures of actually observed comparisons and reductions; in a manner, the roots of the figures used as statements of length.
Sir Joseph Whitworth gives 1/40000 of an inch as the smallest length that can be measured with certainty, with an ultimate possibility of 1/1000000 of an inch; but imperceptible variations of temperature affect these infinitesimal [4] lengths to such an extent that he believes the limit can only be reached at a standard temperature of 85° F., to avoid the effect of heat of the body. ”

“ This proposal was not favorably received, and the Academy, at the request of government, appointed as a commission Borda, Lagrange, Laplace, Monge, and Condorcet, to decide whether the seconds pendulum, the quarter of the equator, or the quarter of a meridian, should be used as the natural standard for the new system of measures. [10] They settled on the last as best for the purpose, and resolved that the ten millionth of the meridian quadrant, or distance from equator to pole, measured at sea level, be taken for basis of the new system, and be called a mètre. ”

“ The units used for different purposes are entirely distinct [23] from the base of any system, and though always referable to such base, are not practically so referred. It therefore seems useless to burden the people with long scientific names in the ordinary transactions of daily life. ”

“ In all sciences Latin and Greek names are given for easier purposes of classification; but the different peoples invariably keep their own household names for daily purposes, leaving prefix and affix to specialists, probably with advantage to both parties. ”

“ Hassler was adopted, and the standard yard defined as the distance between the 27th and 63d inch marks, at the temperature of 62° F., on the brass scale 82 inches long, being an exact copy of Sir George Schuckburgh’s standard, made by Troughton, of London, for the Coast Survey, and deposited in the Office of Weights and Measures at Washington. ”

“ The following reductions have been given for the United States yard in English inches:
[15]
To Mr. Hassler’s reduction the name of United States inch has been applied; but his reduction is not correct, as he used a rate of expansion for brass deduced by himself of 0·0003783 inch in one yard for 1° F., and later experiments show that the smaller rate of 0·000342, deduced by Airy, is more correct.
By correcting Hassler’s reduction with the later rate of expansion, J. E. Hilgard shows that the difference would be very small, or only 36·0002286 = 1·00000635, or about 2⁄5 of an inch in a mile. ”

“ During the preparation of this investigation of Standard Measures a large number of authorities were examined, including the following: Kelly’s “Universal Cambist,” Maunder’s “Weights and Measures,” “Encyclopædia Britannica,” “Chambers’ Encyclopædia,” Williams’ “Geodesy,” Hymer’s works, “Smithsonian Reports,” “Coast Survey Reports,” Herschel’s “Astronomy,” etc. The only concise and clear statement I found was J. E. Hilgard’s report to the Coast Survey on standards in 1876, which I was gratified to find coincides with my deductions.
Arthur S. C. Wurtele. ”