Report of the Kew Observatory Committee. 



I. Magnetic Observations. 



The Magnetographs liave been in constant operation throughout 

 the year, and the usual determinations of the Scale Values were made 

 in January, 



The ordinates of the various photographic curves representing 

 Declination, Horizontal Force, and Vertical Force were then found 

 to be as follows : — 



Declinometer : 1 cm. = 0° 8'' 7. 

 Bifilar, January 11th, 1898, for 1 cm. SH = 000051 C.G.S. unit. 

 Balance, January 12th, 1898, for 1 cm. BV = 0-00050 C.G.S. unit. 



Owing to the gradual secular change of declination, the distance 

 between the dots of light upon the cylinder of the magnefcograph 

 had become too small for satisfactory registration, and it Avas found 

 necessary to alter the position of the zero line. From a similar 

 cause it was also found necessary to re-adjust the balance of the 

 vertical force magnetometer. 



During the past year two magnetic storms, or periods of con- 

 siderable disturbance of the needles, have been registered, the first on 

 March 14-15, the second on September 9-10. 



The extreme amplitude of the March disturbance was : horizontal 

 force, 0-0050 C.G.S. unit; vertical force, 0'0057 C.G.S. unit, and 

 declination, 1° 26'. In eight minutes, from 10.40 to 10.48 p.m. on the 

 15th, the horizontal and vertical components exhibited falls of 002 

 and 0*003 C.G.S. unit respectively. The most rapid change of 

 declination occurred some thirty minutes later. Speaking generally, 

 the most salient features were fche large falls in both the horizontal 

 and vertical components and the movement of the declination needle 

 nearly 1° east of its normal position. 



The second storm occurred on September 9 — 10. The principal 

 disturbance commenced somewhat gradually about noon on the 9th, 

 but one of its most striking features was an exceptionally rapid fall 

 occurring simultaneously at 3.5 p.m. in the horizontal and vertical 

 forces and in the westerly declination. The fall was so rapid as to 

 be shown somewhat indistinctly on the photographic traces, but it 

 amounted to at least 15' in the declination and 0'0023 C.G.S. unit 

 in the horizontal force. The recovery from this fall was also 

 rapid. 



The decimation needle, on the same day, between 5.15 p.m. and 

 8.8 p.m. receded 54' to the east, then turned and in the course of the 

 next thirty-two minutes moved 59' to the west. The horizontal force 

 attained its extreme maximum and minimum at 2.42 p.m. and 



