1520 defn - evry ferlet within the said Isle shall be made of the quantitie of thirtene pottels measured with wheate, stricken measure, evry pottel conteynynge thre wyne quarters, Chester measure, and that one ferlet and pottel to the like quntitie and proporcon shall be made and sealed to be kept within eyther of the castels, to the entent that from tyme to tyme the cuntry measures may be reformed and scaled as occasion shall require.

As the quest would often avouch recourse can be made to www.manxnotebook.com/manxsoc/msvol21/p210.htm