The second and more common weight is called Avoirdupois, being fuller and larger weight than the other, for it contains 16 ounces or 128 drams, viz. 384 scruples, viz. 7680 grains, by this are weighed all kinds of grocery ware and base metals, as iron, copper and brass, as also hemp, flax, rosin, pitch, tar &c.
A century later we find not much improvement in the idea of the pounds Troy and Averdepois.
‘The pound or 7680 grains avoirdupois equals 7000 grains troy and hence 1 grain troy equals 1·097 avoirdupois’ (Rees’ ‘Encyclopædia,’ 1819). This is an example of the utter muddle the Troy pound had made in the minds of otherwise intelligent people.
Similar pedantic efforts were continued, well into the nineteenth century, to represent the Troy pound as the sole standard of England and the averdepois pound only respectable as an offshoot of the royal pound used for vulgar purposes.
The Assize of Bread
Such fictions were helped by the old statutes which compelled the sale, first by Tower and then by Troy weight, of bread as well as of gold, silver, and medicines. And confusion was made worse by the use for a long period of a third weight for bread, the Amsterdam or Scotch troy pound.
The peck loaf, supposed to be that produced from a peck of flour (16 pints), was to weigh 16 of these pounds = 17 lbs. 6 oz. averdepois, the quartern loaf 4 = 4 lb. 5 oz., and the pint loaf (to be sold at a penny when wheat was 4s. a bushel or 32s. a quarter) was to weigh one pound = 17 oz. 6 drams averdepois. The periodical Assize of Bread fixed the price of the peck loaf.
It appears then that the pound of bread was = 7600 grains, its ounce = 475 grains, which was about the Scottish (and Dutch) troy standard. It was probably adopted as coinciding with the weight of bread supposed to be produced from a pint of flour and as keeping up the old superstition that bread must be sold by troy weight. As some persons in authority did not share the stupidity of those who considered the averdepois pound to be 16 troy ounces, the Scottish 16-ounce pound of troy standard was imported for the purpose.
This weight was abolished by 8 Anne (1710) and the sliding scale was put in the averdepois equivalent.
The Assize of Bread was abolished in 1815, but traces of it remain in the name ‘quartern loaf,’ although this now means a loaf of 4 imperial pounds. It may also mean a loaf weighing the quarter of a 16-lb. stone.