This manufacture was remarkable for its extreme rapidity--an excellent brick earth was to be found at almost any point in the Nile valley. An unpractised labourer can easily make a thousand bricks a day; after a week's practice he can make twelve hundred, and, if paid "by the piece" as many as eighteen hundred a day.[49] Sometimes drying in the sun was thought sufficient; the result was a crude brick which was endowed with no little power of resistance and endurance in such a climate as that of Egypt. When baked bricks were required the operation was a little complicated as they each had to pass through the kiln. Egyptian bricks were usually very large. Those of a pyramid in the neighbourhood of Memphis average 15 inches long by 7 wide and 4-3/4 inches thick.[50] After the commencement of the Theban epoch they were often stamped with the royal oval--as the Roman bricks had the names of the consuls impressed upon them--and thus they have preserved the dates at which the buildings of which they form part were erected (Fig. 33).[51] [49] MARIETTE, _Traité pratique et raisonné de la Construction en Égypte_, p. 59. All these operations are shown upon the walls of a tomb at Abd-el-Gournah (LEPSIUS, _Denkmæler_, p. 111, pl. 40). Labourers are seen drawing water from a basin, digging the earth, carrying it in large jars, mixing it with the water, pressing the clay into the moulds, finally building walls which are being tested with a plumb-line by an overseer or foreman (see also Fig. 16). [50] PRISSE, _Histoire de l'Art Égyptien_, letter-press, p. 179. [51] LEPSIUS (_Denkmæler_, part iii. plates 7, 25A, 26, 39) has reproduced a certain number of these stamped bricks. [Illustration: FIG. 33.--Brick stamped with the royal ovals; from Prisse.]