238 



Reports on Special Researches 



Table 12 F. Results of Inclination Comparisons at the Helwan Observatory {Series III). 



'All values are referred to S; .S = "hut"+0'.0. 

 Table 12 G.Sununary of Values of (C. /. W. -Helwan) for 190S-191J,. 



Referring the results to I. M. S. (see p. 273), we obtain: 



(12) I. M. S.- Helwan (Elliott magnetometer No. 87)= +0'.3 (I90&-1 1). 

 (i2a) I. M. S.- Helwan (Elliott magnetometer No. 87)= -0.00056// (191 1 14). 

 {Mb) I. M.S.-Helwan (Dover dip circle No. 193)= + 1M (1908-14). 



NO. 13 HONGKONG OBSERVATORY, CHINA. 



The comparisons for dechuation and horizontal intensity at the Hongkong Observatory 

 were made in the observing house and at an outside or tent station (J5) distant 14.33 meters 

 from the south pier in the observing house and in true bearing south 2 08'.7 east of this 

 pier. The Observatory instruments used were: Elliott magnetometer No. 55 and Dover 

 dip circle No. 71 (needles 3, 4, 7, and 8). The north pier (^-1) of the observing house is 2.55 

 meters from the south pier {A ') ; A is used for the magnetometer and A ' for the dip circle. 



The 1908 D and H comparisons were obtained by simultaneous observations by the 

 Observatory with No. 55 and the C. I. W. observer (D. C. Sowers) with C. I. W. magneto- 

 meter No. 10. Those of 1907 and 1911 were all made by Observer C. K. Edmunds, observ- 

 ing with both magnetometers alternately so that the mean time of the observations with the 

 C. I. W. magnetometer (No. 2 in 1907 and No. 12 in 1911) would be practically the same 

 as for the Observatory instiaiment. No. 55. It should be remarked that the Observatory 

 also has a magnetometer No. 83, of the same pattern as No. 55 and purchased in 1897, but, 

 so far as known, no use of this newer instrument has been made other than for some observa- 

 tions in 1898 from which it was found that at that time No. 55 required an //-correction on 

 No. 83 of -f 527 = -KO. 00141//. 



The dip comparisons of December 1908 were not satisfactory. New comparisons 

 were, therefore, made at the first opportunity during March 1 to G, 1911; the two stations, 

 A' and B, were occupied. The observations were made by Observer C. K. Edmunds, 

 alternately with the two instruments set up at the two stations. The observations were 

 made with two needles of one instrument at station .4', tlien with four needles of the other 

 instrument at station B, and finally with the remaining two needles of the first instrument 



