222 



Reports on Special Researches 



NO. 4.~ANT1P0L0 OBSERVATORY. NEAR MANILA, PHILIPPINES. 



The Observatory is located at Antipolo, about 18.5 kilometers east of Manila. Three 

 stations were occupied : station A is the pier of the absolute observatory ; stations B and C 

 are on the broad road or walk in front of the variation observatory and in line with the small 

 bungalow to the rear of the hotel. B is about 26 meters south of the southeast corner of the 

 variation observatory, and is distant from C 26.71 meters. The marks used for the decli- 

 nation observations were a mark on the bungalow to the south and the Observatory mark 

 on the mango tree 59.86 meters distant from C. 



The absolute instruments used at the Observatory were, at the time: Elliott mag- 

 netometer No. 28, Dover dip circle No. 7 (needle No. 2), Coast and Geodetic Survey mag- 

 netometer No. 17, and Coast and Geodetic Survey dip circle No. 37 (needle No. 2). Mr. 

 C&areo Duluena, of the Observatory staff, observed with magnetometer No. 28 and dip 

 circle No. 7 ; the other instruments, including the ones of the Coast and Geodetic Survey, 

 were used by Observers H. M. W. Edmonds, H. D. Frary, and H. F. Johnston, of the Car- 

 negie. The Carnegie instruments compared with were: C. I. W. magnetometer No. 4 and 

 Schulze earth inductor No. 2. 



The observations with Coast and Geodetic Survey magnetometer No. 17 and dip circle 

 No. 37 showed that both instruments were in need of thorough overhauling. The lifting 

 wyes of No. 37 required adjustment and rust spots were found on the pivots of the dip needle 

 (No. 2). It is, accordingly, not worth while giving in detail the results of the comparisons 

 with these two instruments. The mean results, when referred to I. M. S. (p. 273), are: 



'All values are referred to station A (observatory pier); ^=B 2'.3. 



