22

HISTORY OF ENGINEERING.

Book L

On a bed of sand, 2 feet 6 inches in thickness, slabs of stone about 5 feet in lengthwere laid flat, and upon them were carried up a few courses with smaller stones.

In the centre was placed a large block (A) scooped out to receive the sarcophagus,which contained the body; over this, at B, was another large stone placed, covering thewhole, and on the lower edge was an inscription, or row of hieroglyphics. This sarco-phagus, of black basalt, is now in the British Museum .

The entrance was by the pit k, and the roof of the chamber was formed of four stones,the two outer being set edge-

ways, and inclined inwards,having the two others placedupon them, forming as it werethe first rudiments of an arch.

Over these was turned anarch, the radius of which was6 feet 2 inches, and the spanII feet, which is a little lessthan that of a semicircle. It iscomposed of four courses, 3 feet10 inches thick ; the stones aredescribed to have been 4 feetlong, and 15 inches in breadth ;at the back the joints werepacked with chips, and the wholehad been grouted with fluidmortar. ( See fig. 31.)

The antiquity of the arch issaid by Mr. Wilkinson, in his“ Egypt and Thebes, ” to betraced to the time of Amunophthe First, who reigned 1540years before Christ; and archesof stone and brick are met within several tombs of a very earlydate.

Fig. 30.

_ He also observes, that if the chambers of the brick pyramids at Memphis , erected

by the successor of the son of Cheops , were vaulted, as he supposes, the antiquity ofthe arch might be carried back nearly 700 years prior to the reign of Amunoph, which is2020 years before our era.

When blocks of stone, cut like truncated wedges, are so placed that they support eachother by their mutual pressure,

22 %

mm

mm

they constitute an arch in ouracceptation of the term ; and itdoes not seem improbable thatsuch a system of constructionshould result from the use ofbricks, in a country wheretimber was not readily obtained,to serve as lintels or dischargingpieces. Brick arches seem thefirst upon record; here theopening is gathered over bythree stones set in the or-dinary Egyptian manner, andthe arch in question, turnedover them, bears no weight, butacts simply as a covering; thereis no indication of an abutmentnecessary to render the worksolid and durable.

Mr. Wilkinson observes thatarches, or similar constructions,in brick, were in use 3370 yearsago, as the name of Amunoph ispreserved on the stucco whichcoats the interior of the vaulted

tomb at Thebes . The stone arch at Saccara still exists, of the time of the second Psa^meticus, who reigned about 600 years before our era, and, from its peculiar construct^there is little doubt that the Egyptians had been long accustomed to the erocti 0