Convert from ounce to fother [lead]

Unit Definition (ounce)
The ounce is a traditional unit of weight. The avoirdupois ounce, the unit commonly used in the United States, is 1/16 pound or about 28.3495 grams. The avoirdupois ounce also equals 175/192 = about 0.911 457 troy ounce or 437.5 grains. The word ounce is from the Latin uncia, meaning a 1/12 part, because the Roman pound was divided into 12 ounces. The word "inch," meaning 1/12 foot, has the same root.

Unit Definition (fother [lead])
The fother is a traditional English unit of weight for lead. The fother, equal to 30 fotmals, was always a little smaller than a (long) ton. The original version seems to have been equivalent to 2160 avoirdupois pounds, and the version still being used in the nineteenth century was equal to 19.5 hundredweight or 2184 pounds.