— 150 — 



times the total area of our earth. What tremendous 

 forces must have been at work in the sun as to have 

 produced such disruption of the photosphere ! 



At Mauritius, the magnets were slightly disturbed 

 from 3 a. m. to 11 p. m. on the 14th, and from 2 to 

 4 p. m. on the 15 ; but on the whole they were quiet 

 until about 3.30 a. m. on the 17th when a great 

 perturbation commenced. From 6.40 to 10.30 a. m., 

 the oscillations were extensive and rapid. They then 

 decreased, and from noon to 3.40 p. m. there was a 

 a comparative calm. At 4 p. m. another great 

 perturbation commenced, and it lasted till 8 p. m., 

 after which the movements gradually decreased. In 

 the first of these disturbances, the declination was 

 least at 7.47 a. m. and greatest at 8.40 a. m. and in 

 the second it went on increasing until 7.50 p. m. 



On the 18th and 19th, the magnets were quiet. 

 But at 1.30 a. m. on the 20th, another storm set in, 

 which lasted more or less until noon on the 21st. The 

 period of greatest activity in this storm was from 

 8 a. m. to 4 p. in. on the 20th, but the oscillations 

 were smaller than on the 17th, At first, the declination 

 decreased until 8.12 a. in. and then increased until 

 9.30 a. m. 



Both on the 17th and 20th, the three magnets 

 (declination, horizontal force, and vertical force) were 

 disturbed at the same time. 



The sun-pictures and the photographic traces 

 obtained from the 11th to the 25th, several of which 



