Most of the painters and sculptors to whom the decorations of tombs and temples were confided must have had recourse to these contrivances, but here and there were artists who had sufficient skill and self-confidence to make their sketches directly upon the wall itself. More than one instance of this has been discovered in those Theban tombs whose decorations were left unfinished. In a few cases the design has been made in red chalk by a journeyman and afterwards corrected, in black chalk, by the master.[320] [320] Upon the preparation of the bas-relief, see BELZONI, _Narrative of the Operations_, etc. p. 175. PRISSE gives several interesting examples of these corrected designs, among others a fine portrait of Seti I. (_Histoire_, etc. vol. ii.) Examples of these corrections are to be found in sculpture as well as in painting. Our examination of the sculptures at Karnak showed that the artist did not always follow the first sketch traced in red ink, but that as the work progressed he modified it, and allowed himself to be guided, to some extent, by the effects which he saw growing under his hands. The western wall of the hypostyle hall contains many instances of this. It is decorated with sculptures on a large scale, in which the lines traced by the chisel differ more or less from those of the sketch. (_Description, Ant._ vol. ii. p. 445.) [Illustration: FIG. 259.--Design transferred by squaring. From Prisse.] As the bas-relief was thus preceded a sketch which was more or less liable to modification, it would seem probable that a similar custom obtained in the case of the statue. It appears especially unlikely that those great figures in the harder rocks which represented such an enormous outlay of manual labour, would be attacked without some guide which should preserve them from the chance of ruin by some ill-considered blow. Did the Egyptian sculptor begin, then, with a clay sketch? There is no positive information on the subject, but in all those numerous bas-reliefs which represent sculptors at work, there is not one in which the artist has before him anything in the shape of a model or sketch to guide him in his task. It is possible that the sameness of his statues, especially of his colossal figures in granite or sandstone, enabled the Egyptian to dispense with an aid which the infinite variety of later schools was to render necessary. The Egyptian sculptor was contented with a few simple attitudes which he reproduced again and again. He doubtless began by marking the salient points and relative heights of the different parts upon his block. The rock was so hard that there was little risk of his journeymen spoiling the material by taking away too much, supposing them to be carefully overlooked. Marble would have been far more liable to such an accident. Even Michael Angelo, when he worked the marble with his own hands, spoilt more than one fine block from Carrara.