Читать книгу The Pyramids and Temples of Gizeh - Flinders Petrie - Страница 16

18. THE station marks of the triangulation consist of holes drilled in the rock or stone, and filled with blue-tinted plaster, as already described (sec. 10). Where great accuracy was needed a graphite pencil lead was put vertically into the plaster. Thus the mark may be scraped clean, if bruised or defaced, without destroying the mark. To enable the station-mark holes of about 1/6-inch diameter to be readily found, and at the same time to draw off attention from them, two 1/2-inch holes, similarly filled, are drilled, in most cases one on each side of each station mark, at 5 inches from it, to the N.E. and S.W. I also utilized some few of Mr. Gill’s bronze station marks, that had escaped the attention of the Arabs. The less important stations, of the rock trenches, are merely marked by a single 1/2-inch hole, filled with blue plaster. The general position of the station marks are shown in the plan of the triangulation on Pl. i.

19. The co-ordinates of the station marks, &c., are reckoned from a line beyond the N. side of the whole area, and from a line beyond the E. side of the area: thus there are no minus quantities. The azimuth of true North on the system of co-ordinates is East of the approximate North of the system, or the azimuth of its Eastern boundary, by

+ 1° 12′ 22″±6″

and the value of the unit of co-ordinates in British inches is

·00508259±·00000003

log. ·7060853±·0000017

or the number of units in the inch

196·750±·001

log. ·2939147±·0000017

TABLE OF CO-ORDINATES OF MARKED STATIONS.

RESULTING CO-ORDINATES OF POINTS OF ANCIENT CONSTRUCTION.