It was settled by this Act (1) that a certain yard-measure, made by an order of Parliament in 1760 by a comparison of the yards then in common use, should henceforward be the _imperial yard_ and the standard of _length_ for the kingdom: and that, in case this standard should be lost or injured, it might be recovered from a knowledge of the fact that the length of a pendulum, oscillating in a second _in vacuo_ in the latitude of London and at the level of the sea (which can always be accurately obtained by certain scientific processes), was 39·13929 inches of this yard: (2) that the half of a double pound Troy, made at the same time (1760), should be the _Imperial Pound Troy_ and the standard of _weight_; and that of the 5760 grains which this pound contains, the pound _Avoirdupois_ should contain 7000; and that, in case this standard should be lost or injured, it might be recovered from the knowledge of the fact that a _cubic inch_ of distilled water at the temperature of 62° Fahrenheit, and when the barometer is at 30 in., weighs 252·458 grains: (3) that the _imperial gallon_ and standard of _capacity_ should contain 277·274 _cubic inches_ (the _inch_ being above defined), which size was selected from its being nearly that of the gallons already, in use, and from the fact that 10 lbs. Avoirdupois of distilled water weighed in air at a temperature of 62° Fahrenheit, and when the barometer stands at 30 in., will just fill this space. On p. 180 we saw that the standard gallon in the Tudor period ultimately depended on the pennyweight, which was, as we found, fixed by being the weight of 32 grains of wheat, dry and taken from the midst of the ear of wheat after the ancient laws of the realm. It was from the descendants of this gallon that the _imperial gallon_ of 1824 was fixed, with a slight modification so as to make it contain 10 lbs. of distilled water weighed in air at a temperature of 62° and when the barometer stands at 30 in. The double pound Troy made in 1760 depended in like fashion for its ultimate origin on the wheat-grains, and it also affords us an interesting illustration of the doubling of the original single unit, such as we find in the heavy _royal_ Babylonian system. We may find further analogies between our own system and that of the Babylonians. Whilst at the Mint gold and silver are weighed for coinage by Troy weight, the copper coinage on the other hand is regulated by the lb. Avoirdupois, the ordinary commercial standard. As already remarked, it is almost certain from the method of elimination that copper was the principal article for which the _royal_ Babylonian system was employed, as gold and silver had separate standards of their own, and corn was sold by measure and not by weight.