To all this add, that, if his work happens to be too voluminous for one single hand, he must trust to those of his journeymen and disciples, who, too often, are neither skilful nor cautious enough to follow their master’s design; and if once the smallest trifle be cut wrong, for it is impossible to fix, by this method, the limits of the cuts, all is lost.
It is to be remarked in general, that every sculptor, who carries on his chisselings their whole length, on first fashioning his marble, and does not prepare them by gradual cuts for the last final strokes; it is to be remarked, I say, that he never can keep his work free from faults.
Another chief defect in that method is this: the artist cannot help cutting off, every moment, the lines on his block; and though he restore them, cannot possibly be sure of avoiding mistakes.
On account of this unavoidable uncertainty, the artists found themselves obliged to contrive another method, and that which the French academy at Rome first made use of for copying antiques, was applied by many even to modelled performances.
Over the statue which you want to copy, you fix a well-proportioned square, dividing it into equally distant degrees, by plummets: by these the outlines of the figure are more distinctly marked than they could possibly be by means of the former method: they moreover afford the artist an exact measure of the more prominent or lower parts, by the degrees in which these parts are near them, and in short, allow him to go on with more confidence.
But the undulations of a curve being not determinable by a single perpendicular, the Contours of the figure are but indifferently indicated to the artist; and among their many declinations from a straight surface, his tenour is every moment lost.
The difficulty of discovering the real proportions of the figures, may also be easily imagined: they seek them by horizontals placed across the plummets. But the rays reflected from the figure through the squares, will strike the eye in enlarged angles, and consequently appear bigger, in proportion as they are high or low to the point of view.
Nevertheless, as the ancient monuments must be most cautiously dealt with, plummets are still of use in copying them, as no surer or easier method has been discovered: but for performances to be done from models they are unfit for want of precision.