TRANSACTIONS OF SECTION A. 4\1 
3. The Origin of the Beta and Gamma Rays from Radio-aclive 
Substances. By Professor E. RutHerrorp, F.R.S. 
4. On a Conductivity imparted to Liquid Air by Alpha Rays. 
By Professor J. C. McLennan. 
5. Magnetic Disturbances, Sun-Spots, and the Sun’s Corona. 
By Rev. A. L. Cortin, S.J., F.R.A.S. 
1. Curves for the period 1898-1911 are compared of mean daily disc-area of 
sun-spots, mean daily range of declination, and horizontal force, and yearly 
numbers of great and moderate magnetic disturbances. The data are contained 
in Father Sidgreaves’ yearly reports of the Stonyhurst Observatory. There isa 
general accord in the curves, but there are noticeable discrepancies. The sun- 
spot area and the magnetic declination rose to a maximum in 1905, fell in 1906, 
and rose again to a subsidiary maximum in 1907. The horizontal force, and the 
numbers of magnetic storms, moderate and great, rose steadily from 1905 to a 
maximum in 1907. From 1907 the sun-spot area declined, the fall from 1909 to 
1911 being particularly rapid. The number of great magnetic storms fell, but 
not so rapidly. But the rapid fall of the sun-spot curve, 1909-11, was accom- 
panied by a marked rise in declination, horizontal force, and moderate magnetic 
disturbances. The mean daily frequency of prominences (Kodaikanal) rose 
steadily from 1905 to 1910, the profile-area was at a maximum in 1908. In 
September 1909 a magnetic storm of exceptional violence occurred. Six other 
great storms occurred in September and October of the same year. The 
recovery of magnetic activity was heralded by these great storms. The mag- 
netic storms occurred near the autumnal equinox. All the bigger sun-spots of 
September and October 1909 were confined within a belt of about 10° each side 
of the solar equator. 
2. The monthly numbers of the great and very great magnetic storms for 
twenty-three years, 1889-1911, exhibit decided maxima near the equinoxes. At 
such times the spot zones appear parallel to the plane of the ecliptic. When the 
earth moves across the plane of the sun’s equator great magnetic storms are more 
frequent. The coronal streamers are long, and are mainly confined to regions 
adjoining the solar equator at periods of sun-spot minima. At such periods the 
prominences are also fewer, and their regions fall towards the equator. The 
long streamers of the solar corona are associated with the regions of prominence 
activity, while shorter plumed streamers—e.g., 1893, 1901, 1905—radiate from 
sun-spot centres. A series of spots and prominences occurring at frequent 
intervals would cause such streamers to be maintained for several solar rota- 
tions. Eclipse photographs—e.g., 1889, 1901—show that the general character 
is preserved for a considerable period. By the cumulative action of successive 
accretions, clouds of charged particles, electrons, might be formed at the ends of 
-the streamers. It is suggested that the entry of the earth into such clouds 
occasions magnetic storms. Several streamers of the solar corona, accompanied 
each by its attendant cloud of particles, would occasion two or more magnetic 
storms during the same passage of a spot, regarded as an index of general solar 
activity, across the sun’s disc. This accords with observed facts, fits in with 
the synodic periodicity of magnetic storms, and possibly obviates the great 
difficulties connected with the theory of the origin of magnetic storms as due 
to the projection of streams of particles from individual sun-spots. The 
Zodiacal light extends from the sun along the ecliptic. 
6. A Machine for Drawing the Curves of Radio-active Changes. 
By F. Soppy, F.R.S. 
