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

WEIGHTS AND MEASURES.

21

October, 1834, both the imperial standard yard and the standard
pound were so injured by the fire as to be quite useless as standards.
The Act of 1835, 5 and 6 William IV. was passed to render more
effectual the preceding Acts. It repeals some of the provisions of the
Act 5 Geo. IV., c. 74, which afford facilities for fraud, and abolishes
heaped measure as liable to considerable variation. The new Act
omits all regulation respecting the form of the measures of capacity.
An uniformity of the ratio of the diameter and depth of cylindrical
measures of capacity would appear to have been a desirable provision.
It is obvious that of two measures in the form of a cylinder, the more
shallow of the two will allow of a larger heap in the form of a cone
above the rim of the measure, than the deeper measure of the same
capacity. This uncertainty was remedied by providing that such
articles of merchandise as before were sold by heaped measure, should
in future be sold by weight. And the Act directs that the uncertain
weight called a stone, shall henceforth consist of 14 standard pounds
Avoirdupois, and a hundredweight of 8 such stones; and a ton of 20
such hundred weights. The Act also provides that all articles are to
be sold by Avoirdupois weight, except gold, silver, platina, diamonds
and other precious stones, and drugs sold by retail; and that such
articles and none others may be sold by Troy weight.
In the year 1838 a Commission was appointed to consider the best
method of restoring the standards of weight and measure which had
been damaged in the burning of the Houses of Parliament. Their
report, with an appendix, was printed in 1841, and presented to both
Houses of Parliament by command of Her Majesty.
They considered that the provisions for the restoration of the yard
by means of the length of the seconds pendulum cannot be carried
out, as several of the elements of reduction were doubtful or erroneous; the reduction to the level of the sea was doubtful, the reduction of the weight of air was erroneous, the specific gravity of
the pendulum was erroneously estimated, and the faults of the agate
planes introduced some degree of doubt.
And as the exact weight of a cubic inch of distilled water is yet
doubtful, the pound weight cannot with certainty be restored, as
directed by the Act. They were, however, fully persuaded that, as
several weights and measures exist which were most accurately
compared with the former standards; by the use of these, the values
of the original standards can be restored without sensible error. And
further that it is always possible to restore standards by material
copies more securely than by any experiments referring to natural
constants, such as the length of a degree at any assigned latitude
on the earth's surface, or the length of the seconds pendulum.
They advised that the standards of weight and of capacity should
be defined, the former by a piece of metal, the latter by a certain
weight of distilled water, without reference to the standard of
length; but that the content of the standard of capacity as ex1pressed by the units of cubical measure dependent on the standard
of length, should be stated as the best determination known.
They advised the adoption of the Avoirdupois pound, and the
abolition of the Troy pound. They considered the definition of the
standard yard and pound in the Act 5 Geo. IV., c. 74, the best
possible, and advised that the definition of the gallon be retained.
After weighing most carefully the advantages and disadvantages of