HISTORY OF ENGINEERING.

Book I.

86

Hero, the disciple of Ctesibius , wrote a treatise on mechanics, wherein was described atlength the various mechanical powers, which were all reduced to the lever; he left alsoanother work, called Spiritalia, in which is an account of the forcing pump, which raiseswater by the elasticity of the air, and was probably suggested by the Egyptian noria,a contrivance in which a number of earthen pots were attached to the periphery ofa wheel for the same purpose.

The Great Wall of crude brick, built by Sesostris, on the east side of Egypt , to defend itagainst the irruptions of the Syrians and Arabians extended from Pelusium along the edgeof the desert by Heliopolis for 1500 stadia, or about 187 Homan miles.

Amasis, who was a great promoter of the arts, erected at Sais a magnificent propylaeum,in honour of Minerva, where stones of prodigious magnitude were used in the construction;Herodotus says these stones, of amazing thickness, were brought from the quarries ofMemphis, and part from the city of Elephantine , which is distant from Sais a twenty-fivedays’ journey ; but that, in his opinion, the work most to be admired was an edifice whichAmasis brought from Elephantine , constructed of one entire stone. To transport this, 2000men, all of whom were selected from the sailors, were employed for a period of three years.The length of this structure on the outside was 21 cubits, its width 14, and itsheight 8. Its length inside was 22 cubits and 20 digits, 12 cubits wide, and 5 high.It was placed at the entrance of the temple, and the reason assigned for its being carriedno further was, that the architect, in consequence of his continual fatigue, was heard to sighby Amasis, who, construing it into an evil omen, obliged them to desist. Some affirm,however, that one of those employed to move it by levers was crushed, for whichreason it was moved no further. This resembled probably the red granite monolith atTel-et-mai, which measures in height 21 feet 9 inclies, 13 feet in breadth, and 11 feet7 inches in depth, outside ; and 10 feet 9 inches, 8 feet, and 8 feet 3 inches, inside.

At Memphis a colossal recumbent figure, 75 feet long, was, according to Strabo , placedbefore the dromos of the temple by this king, as were also masses of granite, 20 feet inheight. At Thebes and other places, as well as the quarries at Syene , arc numerousinscriptions, which indicate the removal of granite blocks of enormous weight, forthe decoration of edifices raised by this prince.

Quarries in Egypt. The granite was obtained from Syene, which is a district reachingfrom the island of Philse, along the whole line of the cataracts; that of the finest qualityis obtained on the banks of the river. *

The beautiful pink or rose-coloured granite, the syenite of the ancients, is very hard,and composed of large crystals, which receive an excellent polish. Two thirds of themass is rose-coloured feldspath; sparkling mica and glassy quartz fill up the intermediatespaces, mixed with hornblende occasionally. Pliny sometimes designates obelisks made ofthis granite as Thebaicus lapis, because it came from the region between Thebes and Syene ,

Another granite, more resembling that of the ordinary kind, is found contiguous to it,with particles occasionally much coarser or finer. To these may be added, the fine-grained granite; the grey, with grey-coloured feldspath; black and white granite,which has white feldspath with black flakes of mica, and oriental basalt; and a verydark kind, which is owing to the abundance of mica.

The sandstone quarries of Hadjar Selseleh furnished the chief part of the building stonefor the temples: they are situated in the sandstone district, and, according to some, thestone resembles the gres de Fontainebleau. When first taken from the quarry it is easilyworked, and may be obtained in lengths of 30 feet or more.

We find stone quarries of great extent on the borders of the valley of the Nile .Limestone was generally employed in all the eaily buildings; and quarries, from whencelarge quantities were taken, may be seen at Masarnh, where there are tablets remaining,cut in the time of Ames or Amasis, the lender of the eighteenth dynasty, who ascendedthe throne about 1500 years before Christ; and from these quarries all the compactmagnesian limestone used in the construction of the pyramids of Gizeh was taken. Thereare other quarries at Tehneh, on the point of a hill, where is a thin deposit of crystallizedcarbonate of lime; numerous nautili are found imbedded in the limestone, some ofwhich are more than 6 inches in diameter.

In examining these excavations, we obtain some knowledge of the early Egyptianpractice of detaching masses of stone, and also a valuable lesson on the saving of bothmaterial and labour. To the Egyptians the difficulty of onstructing a pyramid was scarcelymore than the removal of stone from the quarry, and building it up in the manner in whichit lay previous to its being detached from the original bed ; the only difference was, thatthe top stones of the quarry became the foundation stones of the pyramid : they were takenaway in layers, all of the same thickness, and built in courses ; and as the work proceeded,the quarry might represent as many steps from bottom to top as the pyramid. The stonewas sure to lie the right way of its bed; and it would be scarcely necessary to mark anoblong stone, after it was detached; its depth being uniform with the others, wouldindicate sufficiently its true position.