Civil Engineering Reference
In-Depth Information
masonry were to be raised ca 150 m have occasioned endless discussion and will
be noted separately.
For this problem besetting construction ramps there is an obvious parallel in step
design (i.e. staircases). h e expedient here (to achieve height in a restricted space)
is to change the direction of the l ights of steps at landings: a change through 90°
with “quarter landings” and a change through 180° with “half landings”. Such a
device was practical for construction ramps and must have been used on occasion.
Since changing the direction of haulage necessitates levering the block around at
the “landing” it is generally supposed that this was combined with levering it up
a step, e.g. 50 cms onto the new l ight, which would be a further gain in minimis-
ing the run.
With this device the question of levering comes substantively into consideration.
Although surprisingly, there is no Ancient Eyptian representation of levering
masonry blocks (this exists in Assyrian art), abundant evidence of the practice sur-
vives in the form of cuttings in massive blocks for engaging levers (in the form of
heavy timber baulks). Levering is applied to massive stone blocks in two senses: to
move them about horizontally and to raise them up vertically. In the former instance
if any sustained motion is required, levering is used as an adjunct to hauling. It is
the i nal adjustment into position on the wall face where levering alone was used
to move blocks horizontally. With respect to raising blocks, although there have
been proposals in special instances (e.g. in pyramid building) to see levering up
used in place of hauling, in general levering up was employed in conjunction with
hauling. Proposals for levering blocks up vertically through a considerable height
are unconvincing practically—cf the use of “rockers” (Clarke & Engelbach, pp. 94,
95, i gs 89, 108). And no one has suggested that large scale cribbing was a standard
device of Egyptian masonry construction. h e use of levering to raise up blocks
then was, in ef ect, to raise them up a succession of steps. An obvious application
of this idea is to work blocks up a wall face of stepped masonry construction.
However while in special instances such practices would have been employed, it
is not viable as a standard procedure of construction with large roughly dressed
blocks—particularly when the external face of the wall is battered.
In short it may be said that in spite of continued consideration (and imagina-
tion) no alternative procedure has been established other than earth ramps and
i lls for raising up the very massive stone temples of Pharaonic Egypt. And here
it should be noted that the use of earth devices extends beyond the building
site. Generally speaking Egyptian temples were erected by the Nile, so that when
building stone was brought to the site from distant quarries it was transported by
Nile boat. However this required some overland transport at both ends. In these
circumstances, where possible, causeways were constructed for hauling the stone
Levering
63
64
229
