262 TRANSIT OF VENUS, 1874. EGYPT. 



extremity of the ridge known as JEBEL JUISHI, which has the advantage of 

 being elevated about 600 feet above the plain of Cairo, and for this reason 

 was tolerably free from the mist that usually hung about the river and low 

 grounds. There was a road leading more than half-way up the hill to some 

 quarries, and a rough path the remainder of the way, over which country 

 carts could be taken with difficulty. Telegraphic communication with the 

 citadel was easily established with the assistance of Salamah Bey, Chief 

 Engineer of Egyptain Telegraph lines. 



The northern meridian was clear to the horizon, and horizontal ground to 

 the eastward in the immediate vicinity of the station permitted the Model to 

 be placed where it could be conveniently observed with all the telescopes. 



The general position of the station is shown in Plate VIII. ; the entire 

 encampment and relative positions of the instruments in Plate IX. The 

 exact position of the Transit instrument, with regard to prominent features of 

 the surrounding country, is fixed by the following bearings taken with the 

 Altazimuth, which was mounted for that purpose over the center of the Transit 

 Pier. The bearings are reckoned from North through East, South, and "West. 

 The North Meridian line fell upon parts of two Mosque-tombs in the same 

 field of view of the telescope as represented in Sketch N, Plate IX. 



o / 



North Meridan Marks (Sketch N, Plate IX.) o. o 



Equatorial Drum of the Khedival Observatory (Sketch K) .. 10. i3 



The Point marked in Sketch W 1 15. 44 



The Point marked in Sketch M 106. 16 



Summit of ruined Mosque near Fort Mokattam (Sketch P) . . 23i. 6 



An angle of the Tower of Fort Mokattam (Sketch Q) 243. 5 



Geometrical Summit of the GBEAT PYRAMID (Sketch R) . 248. 23| 



Vane of Minaret of Mosque of Mohammed Ali in the Citadel 



(Sketch S) 270. 5 



The position of the center of the transit axis was permanently marked in 

 the following manner: The stones being removed, a hole was bored in the 

 rock, a few inches deep, in which a small piece of iron was inserted and fixed 

 with Portland cement ; this was covered with layers of cement, sand, and soft 

 surface rock. Probably, by reference to the plan and bearings, no difficulty 

 would be experienced in recovering the spot. The transit piers were left 

 standing on the slab to the immediate South of their old position, but were 

 liable to be soon broken up and carried away. 



C. ORDE BBOWNE. 



