PROCEEDINGS 



OF 



THE ROYAL SOCIETY. 



" Magnetic Observations in Egypt, 1893 — 1901." By Captain 

 H. G-. Lyons, K.E. Communicated by Professor Euckek, 

 Sec. B.S. Eeceived June 6, — Eead June 20, 1901. 



The following Magnetic Observations have been made at various 

 times during the years 1893 to 1899, at first with a Declinatorium, 

 made by Bamberg, of Berlin, the property of the Egyptian Govern- 

 ment, and later w T ith a Kew Magnetometer, No. 73, and Dover's Dip 

 Circle, No. 99, both kindly lent by the Council of the Eoyal Society 

 on the recommendation of Professor A. W. Eiicker, F.E.S. These 

 observations are most conveniently divided into five groups, each of 

 which includes observations made during a single period and with a 

 single instrument — 



I. Observations made with a Declinatorium by Bamberg, of Berlin : 



(a.) In the neighbourhood of Cairo, 1893—1894. 



(b.) In the Lybian Desert, near the Kharga and Dakhla Oases, in 



December, 1893, and January, 1891. 

 (c.) In the Lybian Desert from the Wadi Natrun to the Baharia 



Oasis, April, 1891. 



II. Observations taken with Kew Magnetometer, No. 73, and 

 Dover's Dip Circle, No. 99, in the Nile Valley from Cairo to the 2nd 

 Cataract, November, 1894, to June, 1896. 



(a.) Declination, (b.) Dip and Horizontal Force. 



III. Observations taken to determine the Diurnal Variation of the 

 Declination. 



IV. Observations taken at Helwan, near Cairo, in November and 

 December, 1898. 



V. Determination of the Annual Variation from the above observa- 

 tions and those of various observers in previous years. 



VOL. lxxi. B 



