Elementary arithmetic, with brief notices of its history... by Robert Potts.

22

WEIGHTS AND MEASURES

the metric system, they decided to recommend (though not with absolute unanimity) that no change be made in the value of the primary
units of the weights and measures of this kingdom, or in the meaning
of the names by which they are commonly denoted.1 They also
thought it undesirable to enforce the decimal system in all parts of
the various scales of weights and measures, even were the attempt
likely to be attended with fewer difficulties than would be experienced
in this country. In their opinion the scale of binary subdivision is
well adapted to the small retail transactions that seldom become the
subject of written accounts, and which constitute a large part of the
daily transactions in every country.
Another Commission of scientific men was appointed in 1843 for
the restoration of the standards, and they made their final report to
the Lords of the Treasury on 28th March, 1854.
On the general adoption of the report, an Act 18 & 19 Vict.,
c. 72, was passed for legalising and preserving the restored standards
of weights and measures, which received the royal assent on 30 July,
1855. This Act repeals certain parts of the Act 5 Geo. IV., c. 74,
and provides that the straight line, or distance between the centres
of the two gold plugs or pins in the new bronze bar, deposited in the
office of the Exchequer, shall be the genuine standard yard of that
measure of length called a yard,2 and the said line or distance
between the said plugs or pins in the bronze bar at 62~ of Fahrenheit's
thermometer, shall be the imperial standard yard.3
1 One of the Commissioners, J. E. D. Bethune, Esq. (though he signed the
report), differed in opinion from his colleagues, and expressed his views in a letter to.
the Chancellor of the Exchequer. One of his proposed changes was, that the stone,
the hundredweight, and the ton, should be abandoned for weights of 10, 100, an(d
1,000 pounds, and adds immediately after, these words: "My own opinion of the
character of these changes is that, if it were possible to substitute privately the
weights and measures which I have proposed, the great mass of the population would
never discover by the mere use of them that any change whatever had been made."
The Commissioners report that they think it probable that not less than 30,000
tons of these weights are now in use, and that the expense of changing them for
weights in the decimal scale would be between ~100,000 and ~200,000. Is the
practical advantage worth the money, and the confusion that would follow?
2 The following description of the new standard imperial yard as restored, is
given in the preamble of the Act:-" The form adopted for the standard of length,
and for all the copies thereof, is that of a solid square bar 38 inches long, and 1 inch
square in transverse section, the bar being of bronze or gun-metal; near to each end
a cylindrical hole is sunk (the distance between the centres of the two holes being
36 inches) to the depth of half an inch; at the bottom of this hole is inserted il
a smaller hole a gold plug or pin, about one-tenth of an inch in diameter, and upon
the surface of this pin there are cut three fine lines, at intervals of about the onehundredth part of an inch transverse to the axis of the bar, and two lines at nearly
the same interval parallel to the axis of the bar; the measure of length is given by
the interval between the middle transversal line at one end and the middle transversal
line at the other end, the part of each line which is employed being the point midway
between the longitudinal lines; and the said points are herein referred to as the
centres of the said gold plugs or pins." The standard yard and pound have been
deposited in the office of the Exchequer at Westminster. Copies have also been
deposited at the Royal Mint, at the Royal Observatory, Greenwich, and with the
Royal Society of London.
In the 147th volume of the Transactions of the Royal Society, pp. 621-702, is
contained a very interesting account of the construction of the new national
standard of length, and of its principal copies, by G. B. (now Sir G. B.) Airy,
Astronomer Royal.
3 Mr. Whitworth, before the Lords' Committee, in 1855, exhibited an inch measure, with an apparatus for testing its length to the millionth part of an inch, and