Length affects the usefulness and value of cloth, but in this precise sale it is an attribute of one identified article, not a separately priced portion of it.
The classical legal analysis says that the attribute is not independently assigned a share of the aggregate consideration. Failure of the represented attribute triggers the buyer’s option, not an automatic reduction of the full price.
Contemporary property agreements may contain additional terms and law; this classical example should not be applied to them without analysing the contract.