Convert from quartern to fother [lead]

Unit Definition (quartern)
The quartern is a traditional English unit of weight equal to 1/4 stone, 3.5 pounds, or about 1.5876 kilogram.

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.