To avoid irregularities, I have made the following rules with regard to the illustrations intended for the Official Report of the Challenger Expedition.
Two finished proofs of each plate or chart are to be sent to me at this office.
One of these the author, of the Memoir to which it belongs, should sign and mark if it may be printed off.
2. The printer is not to proceed with the printing off of any plate or chart, until he receives from this office, a proof signed by me and marked „to be printed off.”