It is at this stage that more particular mention may be made of the use of the roulette to correct by hand, on the zinc block, the misinterpretations of the process. The roulette consists of a sharp-edged toothed wheel of minute proportions, which is passed backwards and forwards across lines which have come up too black, thus breaking such lines into tiny dots, which therefore print greyer.
It is well to know that such a revision of the block, as first turned out, is possible, and we shall sometimes be glad to make use of it. Still, as before pointed out, such hand-work must not be relied upon.
CHAPTER XI.
OTHER METHODS ADAPTED FOR LINE REPRODUCTION.
When a large space is required to be covered with an even tint, an immense saving of labour and time may be effected by the use of "Shading media"; but beyond a mere saving of labour they may, if discreetly used, be made to produce some very desirable effects.