A sheet of foolscap measures about 17 in. x 13 in. " post " 19 in. x 15 in. " crown " 20 in. x 15 in. " demy " 22 in. x 17 in. " royal " 24 in. x 19 in. " imperial " 30 in. x 22 in. " elephant " 28 in. x 23 in. " atlas " 34 in. x 26 in. The only paper used, as a general rule, for making up into 8vo books is foolscap, post, crown, demy, royal, and imperial; 4to books are made up of all the sizes; though elephant and atlas are chiefly devoted to folios. I now take leave of this branch of the subject, and return to water-marks, which, as previously stated, were formerly used, as they are now, for trade marks, and as trade marks only. Before the year 1320, paper was very rarely used to write upon, but still there are a few examples of it having been so employed extant, the chief of which is an account-book preserved at the Hague, commencing with the year 1301. The water-mark on the paper of this book is a globe surmounted by a cross, while on paper of a little later date the rude representation of a jug frequently appears. The globe and the jug are consequently the most ancient water-marks yet discovered, and these became the principal marks on paper, then exclusively manufactured in Holland and Belgium. The "can and reaping hook" appeared a little later, so did the "two cans," the "open hand," and the "half _fleur-de-lis_," all executed, as might be expected, in the rudest possible manner. The Holbein family at Ravensburg--a town famous to this day for the manufacture of paper--used a "bull's head". Fust and Schoeffer (_circa_ 1460) used a "clapper" or rattle, which has a somewhat curious history. At Ravensburg there was an hospital for lepers, and whenever any of the inmates had occasion to leave the building he was strictly enjoined to flourish a rattle with which he was provided, so that healthy folk could get out of his way. Paper made at the town is often found marked with the rattle, that having grown, by reason of its frequent use, into an institution of the place. The next marks in point of date are in all probability the "unicorn," "anchor," and the "P" and "Y," the initials of Philip of Burgundy and his wife Isabella, who were married in 1430. The famous English printer Caxton (_c._ A.D. 1424-91)[4] used the "bull's head" paper from Ravensburg, the "P" and "Y," the "open hand," and the "unicorn"; sometimes even the "bunch of grapes," which came from Italy. The first folio of Shakespeare's works (1623) has paper marked with a "fool's cap" among other devices. The "post horn," another favourite device, which has given the name to a particular size of paper--namely, "post"--was first used about the year 1670, when the General Post Office was established, and it became the fashion for the postman to blow a horn.