Before speaking of the branch of engraving known by the name of stipple, it would be well to say a few words as to the mode of printing in colour, so prevalent at one time, and of the connection which the works of Kirkall had in relation to the method. Edward Kirkall, born at Sheffield in the year 1722, published a set of plates, in the printing of which he made use both of mezzotint and etching on copperplate combined with wood blocks (that is to say, one printing was from a copperplate, the remainder from wood blocks), in order to give variety of colour to a set of chiaroscuros and other engravings which he executed at that time. His plan differed from that of Leblond in that he used only one copperplate printing, the other tints being given by wood blocks; the results were interesting and effective, partaking more of the character of chiaroscuros, the name he himself gave to them. Apart from the failure of Leblond to realise his ingenious idea that, by the consecutive and proper superposition of three layers of primitive colours, every shade of colour might be produced in the print, there still remained another fatal defect in the process: all his colours were impressed by copperplate printing, that is, he made use of three plates successively printed one after the other on the same sheet of paper. Now a person who can realise the heavy pressure under which a copperplate has to pass so as to force it into the damp paper, in order that the paper should extract the ink from the grain in which it is held, will be able to see that the second and third printing--no matter how accurate the register--must crush the grain or burr given to the paper by the previous printing and thus destroy the beauty of the engraver's work. Notwithstanding the really remarkable results produced by Leblond, this fatal imperfection mars all the engravings he has left executed in this manner. The copperplates which were printed in colour and carried to such perfection, particularly in England, about the close of the eighteenth century, were printed from one plate, generally executed in stipple, and the various tints or colours carefully rubbed in by the printer, who used for this purpose a sort of stump instead of the ordinary dabber. Whatever artistic harmony in colour might be produced was therefore partially the work, and to the credit of the printer; the printed impressions were in addition generally touched up afterwards, and in some cases almost entirely coloured by hand. Every impression printed in colours necessarily varies; some are really exquisite in their delicacy of tone and assemblage of shades, while others are contemptible in their staring vulgarity. Kirkall engraved an elaborate ornamental form on which to give a receipt to his subscribers for these engravings; one of which, running thus, "Receipt from Sir Hans Sloane of one guinea as part payment for twelve prints in chiaroscuro which he (Kirkall)