THE SUN AND SUNSPOTS MAUNDER 171 



with the solar rotation, and the tables show at a glance that the 

 greatest displays synchronized with the return of certain special 

 meridians to the center of the sun's disk ; other meridians on the sun 

 appear to leave our atmosphere quite undisturbed. The sun is struc- 

 tured, not only as between the northern and southern hemispheres, 

 and as between different latitudes, but — as regards its emanations — 

 as between some of its longitudes also. 



There are such influences proceeding from the sun, and the outer 

 corona is built up in obedience to them. This has been clearly seen in 

 the photographs which have been secured of the corona on many 

 occasions; as, for example, in the eclipse of December 12, 1871, photo- 

 graphed at Baikul by Lord Lindsay's assistant, Mr. Davis, and shown 

 in the Memoirs of the K. A. S., 41, Plates 7 and 8. The chief feature 

 of the corona of this eclipse was the massing of its greater portion 

 into petal-shaped formations, which were called at that time " syn- 

 clinal groups." In Plate 7 the synclinal group in the south-southeast 

 rises above a bright semicircular arc, and much fainter arches can be 

 discerned rising above the lowest one. Above the highest of these 

 the sides of the structure curve as if to meet; in Plate 8 they very 

 nearly meet. Several similar synclinal groups were yet more distinctly 

 shown in the photographs obtained by Sir W. H. M. Christie in the 

 eclipse of 1898 at Sahdol in India, and again in the eclipse of 1901, by 

 the members of the British expeditions to Sumatra and Mauritius. 



But it was in the eclipse of 1898 that the structure of the outermost 

 corona was photographed; and the synclinal groups, so beautifully 

 shown on Sir W. H. M. Christie's negatives, were seen on photographs 

 taken at Talni, with a Dallmeyer astigmatic lens of iy 2 inches aper- 

 ture and 9 inches focus, to terminate in long narrow straight beams, 

 the apex of the highest arch in each of the groups being, as it were, 

 blown out, and driven away in a straight line into space. The longest 

 beam was traced for at least 6,000,000 miles. 4 



From photographs taken in these and other eclipses, it would ap- 

 pear that over certain disturbed areas of the solar surface leaf -shaped 

 structures are built up, from the apices of which matter seems to be 

 driven away in long straight rod-like beams. Such beams, driven 

 forth into space and continually replenished from beneath, would, if 

 in the right direction, from time to time overtake the earth in its orbit, 

 and strike it on the sunset arc. Remembering that in a hot gaseous 

 body like the sun, electrified particles, both positively and negatively 

 charged, must occur in great numbers, we can understand how the 

 same disturbed area may be fed with particles of different sign, which, 

 by their mutual attraction, give rise to the rod-like beams that issue 

 from it. These cross the space that separates the earth from the sun, 

 and reveal their arrival here by means of magnetic storms and aurora?. 



♦Knowledge, for May, 1898, pp. 107-109. 



