Previously (Jan 21 2017, 09:21 PM, DozensOnline, Applications, “All Your Base Are Belong To Us”; Apr 28 2017, 08:47 PM, “Requirements For Implementation Of Uncial”) was proposed how using division of the day by a power of the dozen, the gravity of the Earth, and the density of water can produce a unit of mass equal to the metric gram. All metric weights can thereby be converted into a coherent dozenal metrology by moving the decimal point to write the weight in grams, followed by changing the notation of the number from decimal to base twelve.
In choosing units of measurement for a dozenal metrological system, for minimum change and least disruption it is preferable to retain existing units wherever it is possible to incorporate these into a dozenal framework. Retention of the maximum number of existing units while allowing dozenal scales of magnitude would suggest that existing units of measurement still in use that already have dozenal ratios of their magnitudes should be chosen. Retention of existing measures acts as a celebration of the people’s choice of dozenal in the history of measurement and evidence for the benefits of twelve as a division. For this reason, I suggested retention of the inch as a unit of length, which is multiplied by twelve to produce the foot, and has been divided dozenally to the pica and point in typography or graphical design.
As mentioned previously (“Base Twelve in Measurement”, Knew’n’Tell, Ideas & Observations, Thought Views, WordPress, 17th Dec 2018), there are “for weight twelve ounces to a pound troy”. The troy system of weights was used in Britain for weighing of pharmaceuticals of medical prescriptions until it was made illegal since the year 1976 for such use as part of decimal metrication. The troy ounce is, however, still legal for use in the trade of investment precious metal bullion. Another pre-metric system of weights still used is the avoirdupois, which forms part of the American Customary and British Imperial systems of measurement. The troy and avoirdupois systems share as a common unit the weight called a grain, which is about 0.0648 grams, but differ in the multiples of this unit in the formation of larger named units. In the troy system, 480 grains form an ounce troy, so 480 * 12 = 5760 grains form a pound troy, 5760 * ~0.0648 g = ~373.25 g. In the avoirdupois system, on the other hand, seven thousand grains form a pound avoirdupois, 7000 * ~0.0648 g = ~453.6 g. But the avoirdupois pound has sixteen ounces avoirdupois rather than twelve, so the avoirdupois ounce is about 453.6 g / 16 = ~28.35 grams, nearly the same as an ounce troy of about ~373.25 g / 12 = ~31.1 grams.
For unification and dozenification of these current and related systems of weight, I propose that their ounces be dozenalised by being rounded to the same thirty grams, which dozenally is two-and-a-half dozen grams. This is the same as a metric ounce that already exists, so it is not a new unit. Additionally, I suggest that the multiples and divisions of this ounce to form the other named units of weight in the systems should as much as possible be the same as or similar to the ratios of units in the troy and avoirdupois systems, but should be changed only where such ratios involve awkward prime numbers in their factorisations, such as the prime number seven seen in the 7000 grains avoirdupois per pound avoirdupois, or where multiples or divisions are overly decimal (Conversion of decimally rounded numbers to dozenally rounded numbers was described earlier at DozensOnline, Number Bases, Dozenal, “Rounding, Surrogates, And Auxiliaries”, May-June 2017). This procedure allows the adjusted units to resemble in magnitude and relations the existing units, and is thereby along the lines of minimum change while at the same time being dozenalised. After conversion of the sizes of the units, it remains only for the numbers to be written dozenally using dozenal numerical notation of twelve phalangeal numerals.
The dozenified troy, which I call the trade weight system, would then be
0.0625 grams = 1 trade grain
1.5 grams = 1 trade pennyweight = 24 trade grains
30 grams = 1 trade ounce = 20 trade pennyweights = 480 trade grains
360 grams = 1 trade pound weight = 12 trade ounces = 240 trade pennyweights = 5760 trade grains
The dozenalised avoirdupois system or unified American Customary and British Imperial weight systems, which I call the system of civil weights, would become
0.0625 grams = 1 trade grain
1.875 grams = 1 civil dram = 30 trade grains
30 grams = 1 trade ounce = 16 civil drams = 480 trade grains
480 grams = 1 civil pound weight = 16 trade ounces = 256 civil drams = 7680 trade grains
5760 grams = 1 civil stone = 12 civil pounds weight
11520 grams = 1 civil quarter weight = 24 civil pounds weight
46080 grams = 1 civil “hundredweight” = 4 civil quarters weight = 96 civil pounds weight
829440 grams = 1 civil ton = 18 civil “hundredweights” = 144 civil stone = 1728 civil pounds weight
Common to both these trade and civil systems are the thirty gram metric ounce and the trade grain of a sixteenth of a gram. Sixteenths and other binary powers are very convenient for weights and are much simpler in dozenal than decimal, as mentioned before (“The Trouble With Base Thirty”, Knew’n’Tell, Ideas & Observations, Thought Views, WordPress, 26th Jan 2019). At first it might have seemed that the old grain being common to both the troy and avoirdupois systems should have been maintained unchanged. However, in effect that would be no change or no dozenalisation, as the value of the old grain would not be a convenient fraction of the dozenal basic unit of weight, and, with the old grain, only one unit would be common to both the troy and avoirdupois, whereas the sixteenth of a gram allows both the grain and ounce to be the same in both systems dozenalised.
Notice too that in the civil weight scheme, the number of civil pounds weight per civil ton is a cubic dozen, which is near the two thousand pounds per ton of the American Customary and is at the same time the dozenal analogue of the thousand or ten cubed of kilograms per tonne of the metric system.
A weight currently used for gemstones is the carat, which was formerly metricated to 0.205 grams and latterly downgraded to the more decimalised 0.200 grams. The carat is said to be derived from a 24th part of a solidus, where a solidus was a 72nd part of a Roman pound weight. Unifying the Roman pound weight or libra with the trade pound of 360 grams, this would lead to 360 g / 72 = 5 grams for the gem solidus, and 360 g / (24 * 72) = 360/12^3 = ~0.2083 grams for the gem carat weight. I therefore propose replacement of the metric carat by this dozenalised carat of 5/24 grams. However, in earlier times, the number of the gold solidus making up a Roman pound was sixty rather than 72, which would produce a gold solidus weight of 360 / 60 = 6 grams, and 360 g / (24 * 60) = 0.25 g or a convenient quarter of a gram for the gold carat weight. This value for the carat is necessary if the number of trade grains making up a carat weight is to be four. However, since the quarter gram value differs so much from the metric carat, I propose that the quarter gram carat be limited to being a unit of the trade system for precious metals, while the 5/24 gram carat would replace the metric carat used for gemstones.
Hence, the system of trade weights can be supplemented with these further weights, where:
5/24 grams = ~0.2083 grams = 1 gem carat = 1 square dozenth trade ounce = 1 cubic dozenth trade pound
0.25 grams = 1 gold carat weight = 1.2 gem carats = 4 trade grains
1.25 grams = 1 trade scruple = 5 gold carats weight = 6 gem carats = 20 trade grains = 1/4 gem solidus
5 grams = 1 gem solidus = 24 gem carats = 1/72 trade pounds weight
6 grams = 1 gold solidus = 24 gold carats weight = 96 trade grains
360 grams = 1 libra = 60 gold solidi = 1440 gold carats weight = 1728 gem carats
The Latin word siliqua can be used for a carat. The Greek word nomisma can be used for a solidus.
References:
https://en.wikipedia.org/wiki/Troy_weight
https://en.wikipedia.org/wiki/Apothecaries%27_system
https://en.wikipedia.org/wiki/Avoirdupois_system
https://en.wikipedia.org/wiki/Ounce
https://en.wikipedia.org/wiki/Carat_(mass)
https://en.wikipedia.org/wiki/Solidus_(coin)

