Heineken describes an edition of the Apocalypse consisting of forty-eight leaves, with cuts on one side only, which, when bound, form a volume of three “_gatherings_,” or collections, each containing sixteen leaves. Each of these gatherings is formed by eight folio sheets folded in the middle, and placed one within the other, so that the cuts are worked off in the following manner: On the outer sheet of the gathering, forming the first and the sixteenth leaf, the first and the sixteenth cuts are impressed, so that when the sheet is folded they face each other, and the first and the last pages are left blank. In a similar manner the 2nd and 15th; the 3d and 14th; the 4th and 13th; the 5th and 12th; the 6th and 11th; the 7th and 10th, and the 8th and 9th, are, each pair respectively, impressed on the same side of the same sheet. These sheets when folded for binding are then placed in such a manner that the first is opposite the second; the third opposite the fourth, and so on throughout the whole sixteen. Being arranged in this manner, two cuts and two blank pages occur alternately. The reason for this mode of arrangement was, that the blank pages might be pasted together, and the cuts thus appear as if one were impressed on the back of another. A familiar illustration of this mode of folding, adopted by the early wood-engravers before they were accustomed to impress their cuts on both sides of a leaf, is afforded by forming a sheet of paper into a little book of sixteen leaves, and numbering the second and third pages 1 and 2, leaving two pages blank; then numbering the fifth and sixth 3 and 4, and so to No. 16, which will stand opposite to No. 15, and have its back, forming the outer page of the gathering, unimpressed.