[5] Numerous references in colophons show that the metal mostly used was brass, e.g. "_Primus in Adriaca formis impressit aenis Vrbe libros Spira genitus de stirpe Johannes_," and the use of Chalcographi as a name for printers. But there are one or two references to printing "_stanneis typis_," with types of tin. [6] Of the first book printed at Venice only 100 copies were struck off, but the number was trebled in the case of its immediate successors. At Rome Sweynheym and Pannartz mostly printed 275 copies, only in a few instances as many as 300. But at the end of the century Pynson was printing at least 600 copies of large books and as many as 1000 of small ones. [7] A very small third group, earlier than either of these, consists of woodcuts with manuscript text. The most important of these is a German _Biblia Pauperum_ quite distinct from those started in the Netherlands. [8] Some early woodcuts were printed by pressing the block down on the paper by hand; for the early block-books, however, the usual method seems to have been to press the paper on to the face of the block by rubbing it on the back with a burnisher. The paper was thus quite as strongly indented as if passed through a press, but the impression is usually less even. The friction on the back of the paper often gives it a polished appearance. As long as this method continued in use it was, of course, impossible to print on both sides of the paper. [9] It is possible that the earliest specimens of block-printing were intended not to be bound in books but to be pasted on walls. In the case of the _Biblia Pauperum_, for instance, the space between the two woodcuts placed on each sheet is so small in some issues that the sheets cannot be bound without concealing part of the pictures. [10] Different issues are distinguished by the signs of wear in the blocks, or occasionally by their being differently arranged, or with changes made in the blocks. In a different edition we have to deal with a new set of blocks. [11] Since this was written the interesting collection formed by Dr. Schreiber himself has been dispersed. CHAPTER III THE INVENTION OF PRINTING--HOLLAND