380 Proceedings of the Poyal Society 
expedition reached Palestine in the most unhealthy season of the 
year, and their leader was invalided home in January 1872. The 
two surveyors, Sergeant Black, R.E., and Corporal Armstrong, R.E., 
were thus left under the care of Mr. C. E. Tyrwhitt Drake, who 
had been attached to the expedition as linguist and archaeologist. 
On the return of Captain Stewart, the Committee of the Palestine 
Exploration Fund honoured me with the offer of the command of 
the survey party, and I reached Jaffa on the 8th of July 1872. In 
the meantime the survey had been successfully started, and after 
measuring the first base in the plain of Sharon near Ramleh, the 
triangulation was extended first to Jerusalem and then northwards 
to Nablus or Shechem, the detail being at the same time filled in 
over an area of 500 square miles. 
The success of this part of the work was due not only to the zeal 
and skill of the two non-commissioned officers, but also in a great 
measure to the tact and experience of Mr Tyrwhitt Drake, whose 
knowledge of Syrian manners and language was invaluable. 
The method of conducting the survey was soon developed into a 
routine which was preserved throughout the course of the field 
operations. The camp having been fixed in a convenient position 
and as centrally as possible, with reference to the proposed work, 
the triangulation was first extended. The highest points within a 
radius of ten or twelve miles from camp, were visited, and at the 
points selected cairns of stone seven to ten feet high were built up 
and carefully whitewashed. In some cases the domes of the sacred 
tombs formed valuable stations, and in the more wooded parts 
of the country it was necessary to clear away the brushwood, 
leaving a lofty stack of branches bound to a central pole marking 
the instrumental station. 
The triangles thus constructed varied from five to fifteen miles side 
according to the character of the country. Several very long lines 
were also observed, and from the ends of the bases astronomical 
observations were taken to fix the meridian lines. The observations 
as calculated at Southampton in 1877 showed an error rarely 
exceeding thirty feet in the mile, which it is unnecessary to remark 
is not visible on paper to the one-inch scale. 
From the trigonometrical stations observations were also taken 
to all prominent objects within the field. It was found, however, 
