Comparisons of Magnetic Standards, 1905-14 



217 



NO. 2.-ALGIERS OBSERVATORY. BOUZAREAH, ALGERIA. 



Comparisons were secured at the Algiers Observatory (Bouzareah Observatoire 

 d'Alger) by Observer W. H. Sligh in January 1912, and again in November and December 

 of the same year; the instruments used by him were C. I. W. magnetometer No. 7 and 

 Dover dip circle No. 202 with needles 1 and 2. The observations were made at 3 stations, 

 designated, 0, M, and ilfo. 



0, the principal station, is the pier in the magnetic hut of the Observatory, this hut 

 being about 50 meters distant from the nearest building; the pier, which is of stone, is set 

 in a cement floor and has a marble top. M is the station where Professor Moureaux had 

 made his observations ; it is about 300 meters distant from 0, and is on the hillside at a place 

 leveled off for observational work, about 150 meters west of the Observatory grounds. 

 M was marked by Mr. Sligh with a wooden peg about 4 centimeters in diameter and about 

 40 centimeters long; the exact point is the brass tack in the top of the peg. M2 was an 

 auxiliarj' station, used by Mr. F. Baldet, of the Observatory staff, in some of his observa- 

 tions and by Observer H. E. Sawyer, of the Department of Terrestrial Magnetism, on 

 October 10, 1912, while making special magnetic observations on the day of the eclipse. 

 Mr. Sawyer marked the spot by a round wooden peg nearly 4 centimeters in diameter driven 

 flush with the ground and ha\'ing a brass tack in the top. M2 is on the first rise west of the 

 Observatory and on the same hill occupied by it ; it is, furthermore, on the brow of the hill 

 overlooking station M and is about 60 meters west of the latter. 



The mark used at for the declination observations was Matifou Phare (Lighthouse) 

 about 19 kilometers distant, its azimuth, as supplied by the Observatory, being 265 28'. 5 

 W. of S. The mark used throughout at M was the Dome de Kouba, about 12 kilometers 

 distant; its azimuth, as determined by Mr. Villatte, of the Observatory, by stellar observa- 

 tions, was 322 46'.7 W. of S. The mark sighted from M2 was the Dome de Kouba; its 

 azimuth was 322 28'. 6 W. of S., as determined from solar observations by Messrs. Baldet, 

 Shgh, and Sawyer. 



Mr. N. Villatte used for the comparisons the Echassoux magnetometer, the constants 

 of which were not definitely known. After the first series of comparisons, made on January 

 5 and 1 1, he remagnetized the two magnets of his instrument on January 24. An examina- 

 tion made after these first comparisons showed that certain parts of the instrument were 

 magnetic. 



Mr. Baldet observed with the Brunner Freres magnetometer and with the Laderriere 

 dip circle, both instruments being of the very small portable type and having been used 

 formerly by Mr. d'Abbadie. During the decHnation observations on January 12, he inad- 

 vertently allowed the two magnets of the magnetometer to come in contact and thus 

 incurred the possibility of a change in his instrumental constants. 



In view of these mishaps and changes, it is not deemed worth while to publish in detail 

 the January series of magnetometer comparisons. The mean results are as follows: 



Table 2A.C. I. W.- Algiers {January 191Z). 



Only one observation, hence not much value to be attached to the result. 



