———=—<—_ = 
A phetiel teel! deg, t 
TRANSACTIONS OF SECTION A. 395 
with the equatorial rays of the sun’s corona, which are such a characteristic 
feature of the corona at times of maximum solar activity. Regions of sun-spot 
activity, with the associated phenomena of facule, Hocculi, and prominences, 
not untfrequently persist for several solar rotations. In a recent series of papers 
published in the ‘Monthly Notices R.A.S.’ (vol. lxxiii., nos. 1, 3, 6, 7) 
several such regions were discussed, which were also associated at each synodical 
return relatively to the earth, with series or batches of magnetic storms. Some- 
times a set of consecutive magnetic disturbances will occur accompanying the 
transit of a region of solar disturbance across the disc, and, after an interval of 
two or three days, other isolated storms, corresponding to positions of the solar 
disturbance widely different in longitude relatively to the central meridian of 
the sun. Such phenomena point to the conclusion that the mode of propagation 
of the solar influence, which conditions the occurrence of terrestrial magnetic 
disturbances, is not in the form of a single cathodic discharge of particles, but 
rather of a divergent pencil of stream lines emanating from a focus of activity. 
The corone of the eclipses of 1893, 1898, 1905, and 1908 were characterised by 
bunches of divergent equatorial rays, the radiant-points or areas of which were 
identified with regions of long-continued sun-spot activity, which were in their 
turn associated with synodical series of magnetic storms, 
A region of sun-spot disturbance was observed in 1910 from August 3 to 
October 24, the spots being confined to a belt between mean longitudes 64° to 
48°, and latitude —13° to —16°. Regions of long-continued sun-spot activity 
are generally in the form of narrow strips on the sun’s surface. At the third 
appearance of this particular group of spots another group broke out just in 
advance of it, as so frequently happens, and the two groups together formed a 
fine curved stream nearly 20° in length, quite visible to the naked eye. The 
life-history of the combined groups can be followed from the Greenwich and 
Stonyhurst records, and that of the great area of the accompanying flocculi 
from the Tortosa observations. Besides compact flocculi centred on the groups, 
there was a region of ditfused flocculi which spread to the north-west of the 
sun-spots. When the combined groups were visible on the sun’s disc, Septem- 
ber 26 to October 9, the whole disturbed region was covered with calcium 
flocculi. ‘The accompanying prominences are discussed by Mr. Slocum in his 
paper ‘The Attraction of Sun-spots for Prominences,’? and by Mrs, Evershed 
in ‘Some T'ypes of Prominences Associated with Sun-Spots.* ‘he prominences 
which were active from August 2 to November 5, extended on October 8 from 
+6° to -—37° on the W. limb, and on their reappearance on the E. limb on 
October 22, when the spot disturbance was dying out, from + 12° to — 36°. 
The heliographic latitude of the earth varied from +6.0 to +5.1 in the period 
August 3 to October 24. he first appearance of the group was marked by one 
great and two moderate magnetic storms, the second by two moderate, the 
third—that of the combined groups—by three great and five moderate, and the 
last by one great and three moderate, containing several synodical series of 
storms. The accompanying prominences were, according to Mrs. Evershed, in 
the form of radiating streaks, which is characteristic of the type associated 
with sunspots. If such radiating streaks represent the stream lines of the 
solar influence active in magnetic storms, they conform in their structure to the 
coronal rays already identified as connected with sun-spot areas and accom- 
panying series of magnetic storms. Mr. Slocum also photographed rays dis- 
posed radially to the spot centres. 
5. A Temperature See-saw between England and Egypt. 
By J. T. Cratca. 
6. Possible Methods for Measuring the Amount of Atmospheric 
Pollution, &c. By Dr. J. S. Owsns. 
The following methods were considered :— 
1. Filtering a measured volume of air through a cotton or asbestos wool 
filter and weighing the filter before and after. This method was used by Mr. 
» Astrophysical Journal, xxvi., no. 4. 
* Monthly Notices R.A.S., xxiii. 6. 
