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Old Units - Weight, Dry Capacity and Liquid Measure

Weight

Just so as to make life really awkward, there were many different systems for weight :- Apothcary, Avoirdupois, Troy (mainly for the more precious metals), Tower, London, Merchant and Butcher, each of which was favoured by a different trade. In the past, these different systems were frequently used simultaneously which would have made it very difficult indeed trying to find the real weight of something - and it was also difficult to know which system might be regarded as the most representative. The system which finally became the most common - and the one we generally used - is the Avoirdupois system which was approved by Elizabeth 1st in 1588. The word comes from the French “avoir” (to have) + “du” (some) + “poids” (weight), ie “to have some weight”. But it’s now defined as having 16 ounces to 1 pound and based on the Grain (as for wheat) and is now further defined as having 7000 grains to the pound. But before this, it underwent a number of different versions before final stability in 1824. An original, and generally accepted table of weight was :-

20 grains = 1 scruple 3 scruples = 1 dram 8 drams = 1 ounce (symbol oz) 12 ounces = 1 pound (symbol lb) 7 pounds = 1 clove 2 cloves = 1 stone (ie 1 st = 14 lbs) 2 stones = 1 quarter (ie 1 qtr = 28 lbs) 4 quarters = 1 hundredweight (symbol cwt = 112 lbs) 20 cwts = 1 ton (or 2240 lbs)

But the above table, down to the level of the pound, has also become what is known as the Troy system and the big difference between the Troy and Avoirdupois systems comes after the ounce when the Avoirdupois system has decreed that there should be 16 ounces to a pound - not 12. It therefore means that the number of grains in a Troy pound = 20 X 3 X 8 X 12 = 5760 whereas in the Avoirdupois system the number becomes 20 X 3 X 8 X 16 = 7680. But for the sake of simplicity, a compromise rounded it to 7000 in 1824.

For those of you for whom this is double-Dutch, the approximate everyday metric equivalents are 28 grams = 1 ounce; 454 grams = 1 lb; 2.25 lbs = 1 kilogram; 6.5 Kg = 1 stone; just over 900 Kg = 1 ton (but 1000 Kg = 1 metric tonne)

The Troy system can also start with the grain and an alternative to the above table is :-

4 grains = 1 carat (as found in precious jewellery) 6 carats = 1 pennyweight (symbol is dwt) 20 dwts = 1 Troy ounce (ozT) 12 ozTs = 1 Troy pound (lbT)

But as shown above, the Troy pound and the Avoirdupois pound are not the same. Life gets very confusing! To make things worse, the Apothcary’s system