Fesruary 8, 1917] 
was affected by it, and had the moon been absent the 
sight would have been truly magnificent. As it was, 
great beams shot up vertically and horizontally, the 
latter forming great arches, and the former appear- 
ing like searchlights. Frequently an immense area 
of the sky would become illuminated as if by a great 
‘cloud of mist, and the light would pass up to the 
zenith with lightning rapidity, appearing like clouds 
of light being wafted upwards from the N. horizon. 
The clouds were mostly greenish, like a gas-mantle, 
but the background of the sky was pale ruby.” 
The magnetic storm of considerable violence which 
accompanied this auroral display affected the magnets 
between the hours January 4, 3.36 p.m., and January 
5, 2.48 a.m., G.M.T. The greatest range in declina- 
tion was 57’, in horizontal force 50’, and in vertical 
force 52', where in force 1'=4-6 y (y=10-* C.G.S. 
unit). Mr. Neate mentions 5.45 p.m. as the hour of 
a lesser display, and Mr. Denning 8.30 p.m. as the 
time of the appearance of an auroral streamer. Both 
these times approximately were marked by rapid oscil- 
Jations in all three elements. The ranges were, in 
the first instance, declination 40:4’, horizontal force 
40:2’, and vertical force 19-6’, and, in the second in- 
stance, 40-0’, 29:7’, and 10-5’ respectively. Dr. Ram- 
baut gives the hour 10.15 p.m. for the finest display 
of streamers, and Mr. Neate the hour 10.45 p.m. 
This period was also marked by a series of oscilla- 
tions on the three curves, but not so rapid or of such 
large amplitude as the former ones. 
On December 30, 1916, a very large round spot of 
regular outline was glimpsed through clouds near the 
E. limb of the sun. On January 4, when it ‘was 
about 13° to the west of the central meridian, it had 
the appearance of an elongated spot with considerable 
penumbra and two nuclei, followed by two smaller | 
spots. Another group of two large spots about the same 
distance east of the central meridian followed it on | 
almost the same parallel of latitude. A small round 
spot was also near the W. limb. These spots, in the | 
northern hemisphere, were all the spots visible on 
that date. The area of the large spot was 9 units, 
in terms of the 1/5000 of the visible disc, and its posi- 
tion was: latitude +14°, and longitude 136°, helio- 
graphic. It was a new _ outburst, 
though conti- | 
guous to a region which had been disturbed as late | 
as October 19, 1916. By January 6 the main spot had | 
split into two, and the surrounding area showed much 
activity. On January 9, when it was near the W. 
limb of the sun, there was a whole series of groups 
of small spots, almost on the same parallel of latitude, 
stretching from the W. to the E. limb of the sun. 
In addition to the large group, which, though born 
on the invisible hemisphere of the sun, was active 
between January 4 and 6, the subsequent appearance | 
of no fewer than five groups of small spots, three of 
which were new formations, was further evidence of a 
disturbed condition of the solar surface. 
24 extensive and bright facule marked the position 
of the large spot on the sun’s E. limb. 
A. L. Cortig, S.J. 
Stonyhurst College Observatory, 
January 25. 
Forms of Weathering in Magnesian Limestone. 
SEVERAL distinct forms of weathering are met with 
in the Sunderland Magnesian Limestone, two of which 
I will describe, leaving two others for another occa- 
sion. In one of them the prevailing rod, or the reti- 
form, structure has been altered into one closely 
resembling a coral, e.g. Lithostrotion basaltiforme. 
Many of the short columns, consisting chiefly of cal- 
cium carbonate, have now numerous thin bands across 
their long axis (shown by arrow), producing the coral- 
NO. 2467, VOL. 98] 
On January | 
NATURE 
447 
like appearance, due, I suppose, to rearrangement in 
a periodic series of the carbonate of lime molecules. 
They have a fairly uniform thickness of about 1/30 of 
an inch, with slightly less interspaces. Thus far I 
have only met with this structure in this unique con- 
cretionary limestone, where it has been exposed several 
years. 
The specimen shown in Fig. 1 was cut off a pinnacle 
Fic. 1.—Weathered Magnesian Limestone, Carley Hill (natural size). 
6 in. long and 2 in. thick, which was removed from 
the top of a ‘‘wall” of rock, this, at the base, is 
| about 1o ft. thick, with a section, on the north side, 
of about 1o ft., and on the other side 20 ft., from the 
respective ground-levels. It is situated on the northern, 
boundary of Old Southwick Quarry on Carley Hill, a 
| part of Fulwell Hill. 
Thicker bands are seen in this figure; the 
Fic. 2.—Segregation banding in Cannon-ball Bed, Roker, 1g01 ( X 1°5). 
| diagonal one, b.o, is what I term a ‘“‘band of origin,” 
from which the rods grew. Others, at right angles 
to the rods, are part of the original ‘‘honeycomb” 
structure. Apparently a few rods remain unaltered, 
| but closer observation reveals the same zones, although 
not distinguishable in the photograph. 
Fig. 2 represents part of a vertical surface on a 
southern face of the Cannon-ball Bed, where it juts 
