RECENT MAGNETIC ST OEMS AND SUN-SPOTS. 167 



I find, by reference to my note-book, that other changes were visi- 

 ble on the 20th, but unfortunately I was prevented from sketching 

 them. After that, unfavorable weather, and other interruptions, pre- 

 vented me from sketching the spot, but the sketches that were made 

 cover the period during which the most remarkable changes occurred, 

 as well as that of the greatest magnetic disturbances. In order to 



Fig. 3. 



obtain a clear notion of the tremendous forces involved in the changes 

 represented in the drawings, it is necessary to consider the enormous 

 size of the spot as measured in square miles. Counting the whole 

 area covered by the various nuclei and the penumbral depression sur- 

 sounding them, the spot was not less than 60,000 miles long and 40,000 

 miles wide. In other words, it covered 2,400,000,000 square miles of 

 the solar surface. The area of the whole surface of the earth, land 

 and sea, is less than 200,000,000 square miles, so that if the crust of 

 the earth had been peeled off like the skin of an orange, spread out flat 

 and plastered against the sun, it would have looked like a mere out- 

 lying patch beside the great congeries of sun-chasms constituting this 

 gigantic spot. Masses of gaseous matter, many times greater than 

 the earth in volume, must have been hurled and whirled about there 

 with tremendous velocity in order to produce the changes which the 

 telescope revealed. Milton's description of the battling elements of 

 chaos, through which Satan fought his way, will apply, though inade- 

 quately, to the scenes of chaotic fury of which such a sun-spot is the 

 theatre. 



In Fig. 4 is represented a very remarkable spot which, because it 



