Havell countermarks (hereafter "watermarks") are parallel to one of the longer edges. They read either
where 18xx is the year the paper was made (1825 to 1838). The Turkey Mill watermark is located at the edge of the sheet, while the Whatman watermark is more towards the middle. Because it is on the far edge of the paper, the Turkey Mill watermark is more likely to be trimmed. On occasion the mark is found slightly trimmed (for example, the bottom of the year missing) even when the sheet is what is considered to be full width.