Again, such paper is of unequal thickness, the writing paper of the period being much smoother and finer than the printing paper, while in parts it is almost certain the ink has run, as it does on a coarse, absorbent paper. This is a sure sign that the paper is printing and not writing.
Further, such paper is certain to show signs of wear at the bottom edges where they have been handled and exposed, while that part of the page which has been closest to the inside edge of the cover is generally cleaner, and shows less sign of wear. In many cases the impression of the book binding is plainly visible.
A careful examination and comparison of a few sheets of genuine letter paper of the seventeenth and eighteenth centuries with the blank leaves found in printed books will reveal differences so marked that mistake is scarcely possible afterwards.
It often occurs that grease marks interrupt the forger. Knowing that he cannot write over them, and that they are hardly likely to have existed on the paper when it was new, and when the letter was supposed to be written, he avoids them. The result becomes apparent in unequal spacing of words and even letters.
On one occasion a really excellent forgery, which had successfully withstood all the tests we had applied, had its real character revealed by a curious oversight on the part of the forger.
It was an early seventeenth century document, and our attention was arrested by a peculiar uniform smudgy appearance, such as results from blotting with a hard, unabsorbent, much-worn sheet of blotting paper. At the period of the presumed date of this document blotting paper was unknown, writings being dried by means of a specially prepared fine powder called pounce, sand, or a powder containing fine crystals of metal intended to give an ornamental gloss to the ink. Close examination under the microscope revealed the truth. There were no signs of pounce or any other drying powder, the crystals of which are usually plain to the unassisted eye, but there were distinct signs of the fibre of the blotting paper left in the ink.
Another forgery we discovered through the presence in the centre of the sheet of paper of a very faint square outline which enclosed a slight discolouration. The sheet had, as usual, been removed from a book, and the square outline was a faint impression of a book-plate which had been affixed to the opposite page. The discolouration was caused by the ink on the book-plate.
It should be superfluous to have to remind intelligent and educated persons that it is necessary for a collector of old documents to make himself familiar with the peculiarities, habits and customs of the period in whose literary curiosities he is dealing. Yet fact compels the admission that extraordinary laxity and even ignorance exist on these points. We are acquainted with a collector, by no means uneducated, who gave a good price for a letter purporting to be by Sir Humphrey Davy, the inventor of the miners' safety lamp, enclosed in an envelope. He was ignorant of the fact that envelopes were unknown until 1840, thirty years later than the date of this particular letter. Envelopes supposed to have been addressed by Dickens have been offered for sale and purchased, bearing postage stamps not in circulation at the period.
One would imagine that a forger would pay sufficient attention to his materials to be on his guard against the blunder which earned the perpetrator of the Whalley Will Forgery penal servitude. He put forward a will dated 1862, written on paper bearing in a plain watermark the date 1870! Another indiscreet person asked the Court to accept a will written and signed with an aniline copying pencil, but dated years before that instrument had been invented.
Both the works by Dr. Scott and Mr. Davies, given in the list, show samples of watermarks of the various periods affected by forgers of literary documents.