Encouraged by the approbation of his wife, and nerved by that passion which urges the inventor onward in the pathway of discovery, Gutenberg undertook the task with alacrity. First he met the difficulty of finding wood suitable for engraving. Some kinds were too soft and porous, others liable to split. After many trials, he selected the wood of the apple-tree. This has a fine grain, is dense and compact, and sufficiently firm to bear the process of engraving. In modern times box-wood is almost exclusively used in this art, as superior to all other species in the qualities required. It is sawed in blocks crosswise of the grain, and these polished and whitened, present a surface almost as smooth as ivory, and capable of receiving the finest touches of the pencil and the graving tool. Another difficulty in his course was the want of tools; his unfailing genius came to the rescue, and tool after tool was contrived, until his tool-box showed an array of knives, saws, chisels, and gravers of various patterns, each one in its turn having been duly admired by the pair of bright eyes that followed his progress. At first Gutenberg drew the portrait of the saint and the inscriptions accompanying it on the same block; but in later experiments he hit upon the idea of having them on separate pieces, the different blocks being nicely fitted together in printing. This was an onward step, which he viewed with satisfaction. “These movable blocks will be of service,” said he to Anna; “for I can complete the picture as well as the letters better in this way, and, when desirable, can embellish the writing with ink of another color.” At length, when the “St. Christopher” appeared, printed from the improved block, Anna exclaimed that it was far better than the old one. “Yes,” replied Gutenberg, “but I perceive that it is not perfect. No picture can be properly executed without thicker ink. This flows too readily, and with all my care I can scarcely avoid blotting.” It required many experiments and much patience to surmount this difficulty of the ink. He found finally that a preparation of oil would best serve his purpose. The color might be varied according to the ingredients used. In the earliest works which have come down to us, it is of a darkish brown, and appears to have been made of umber. This was chosen probably in imitation of the old drawings which served as copies. A mixture of lamp-black with oil gives a black ink; and this is substantially the composition of printer’s ink at the present day. As Gutenberg experimented, Anna watched his progress with excited interest. When he had succeeded in preparing an ink of suitable quality, she saw that he needed some means of spreading it evenly upon the block.