AN engraver of any ability may engrave upon a plain block, a block on which there is no drawing, no indication whatever of what he is about to do. He can engrave (as he can draw) “out of his own head,” improvising his subject; or he may engrave from a picture or copy before him, as is done by the engraver in steel or copper. But he has not the facilities of the copper-engraver, who can draw or trace his most delicate outlines, strengthen, alter, or remove them as needful, and then add the shadows, elaborating more and more as he may find occasion. The wood-engraver can not so alter or remove. Everything is done at once, and what is cut remains. He may indeed cut away more wood, so lightening and sometimes giving tone to certain parts of his subject; he may clear away altogether: but there is the limit of his power of alteration or amendment. It is therefore desirable that there should be some guide for him on the block before he begins to engrave. In all “black-line ” work, such as has been already described, it is absolutely necessary to have every line drawn upon the wood, except perhaps a mere series of shadow lines, which the engraver might be allowed to give at his own discretion, but even then the colour to be obtained by those lines would have to be shown by a tint washed on the block. The fineness or coarseness of these shadow lines, perhaps their direction and character, might be left to the engraver. Not so much as this was left to the early wood-cutters or engravers. Every line was distinctly drawn.