12 PERCY SLADEN TRUST EXPEDITION 



northward of the trigonometrical station on Observatory Point (see Admiralty Chart 

 No. 920, Diego Garcia), beneath three or four coconut palms. 



The position is marked by a flat coral slab, with ^ roughly cut in it, buried about 

 one foot deep in the ground, and covered with a small cairn. It is placed at the south 

 side of the path, and at about six feet from the present landward edge of the sand. 



From the position, the right extreme of the trees on Eclipse Point (in 1905), bears S. 

 68° 21' 05" W. (True). 



On June 12th, 1905, the magnetic elements found at this spot were as follows: 



Declination. 



At 9 h. 30 m. a.m. 4° 42' 41" W. 



„ 3h. 45 m. p.m. 4° 32' 51" W. 



Inclination. 

 From 2 h. 00 m. to 2 h. 45 m. p.m., - 34° 24' 18". 



Horizontal Force. 

 From 11 h. 20m. A.M. to Oh. 33m. P.M. X' = 0-31268 c.g.s. 



Coetivy Island. 



The Magnetic Observation Spot, which is in Lat. 7° 09' 46" S., Long. 56° 14' 56" E., 

 is about 300 yards south of the Settlement Flagstaff, and 20 yards in from the high 

 water line. A Casuarina tree (the local name is " Filao "), with three trunks, stands on 

 the end of the slight outward bend of the beach at this point, and upon its southern 

 trunk a mark ^ is cut at five feet from the ground. 



The exact position of the spot is marked by two large, faced coral blocks, mortared 

 one on top of the other, and buried about eighteen inches under the ground. 



yf^ is cut on the top of the upper block; the circular hole representing the precise 

 position; and the words " SEALARK, 1905 " are cut on the side. 



This stone is S. 48° E. (Magnetic) from the marked Casuarina tree, distant 52 ft. Oin. 



The " Fixed Mark " used in the declination experiment was the centre line of the 

 Settlement Flagstaff. Its azimuth is N. 3° 09' 29" E. 



The following magnetic elements were observed on this position on September 11th, 

 1905: 



Declination. 



At 10 h. 14 m. a.m. 3° 40' 45'6" W. 



„ 4h. 04 m. P.M. 3° 40' 37-9" W. 



Inclination. 

 From 1 h. 28 m. to 2 h. 23 m. p.m., - 35° 58' 42". 



Horizontal Force. 

 From 11 h. 22m. a.m. to Oh. 40m. p.m. X' = 0-30103 c.g.s. 



