July 15, 1886] NATURE 257 
hydrogen that there is little doubt that we are in the presence of ; been recorded during eclipses which have happened at the 
cause and effect. The hydrogen, I am now prepared to 
believe, is a direct consequence of the dissociation of the metallic 
elements. 
It will be convenient to refer here to the facts which 
been recorded during those eclipses-which have been observed 
at the sunspot minimum and maximum. 
At the minimum the corona dim; observations 
during the minimum of 1878 showed that it was only 
seventh as bright as the corona at the preceding maximum. 
There are no bright lines in its spectrum, and both photographic 
and eye-observations proved it to consist mainly of a ring round 
the equator, gradually tapering towards its outer edge, which 
some observations placed at a distance of twelve diameters of the 
sun from the sun’s centre. 
The same extension was observed in the previous minimum in 
1867, and the polar phenomena were observed to be identical in 
both eclipses. At the poles there is an exquisite tracery curved 
in opposite directions, consisting of plumes or Aanaches, which 
bend gently and symmetrically from the axis, getting more and 
more inclined to it, so that those in latitudes 80° to 70° start 
nearly at right angles to the axis, and their upper portions droop 
gracefully, and curve over into lower latitudes. 
Although indications of the existence of this ring have not 
have 
made 
one- 
is 
period of maximum, there was distinct evidence both in the 
eclipses in 1871 and 1875 of the existence of what I ard as 
the indications of outward upper polar currents observed at 
minimum. 
The fact that the solar poles were closed at the maximum of 
1882, while they were open in 1871, is one of the arguments 
which may be urged that at times the whole spot-zones are 
surmounted by streamers, with their bases lying in all longitudes 
along the zones. 
It was probab 
reg 
y the considerable extension of these streamers 
earthwards, in I which hid the finer special details the 
poles, while in the part of the sun turned towards the 
earth was not rich in streamers of sufficient extension. 
Touching these streamers, it is an important fact to be borne 
in mind, that no spots ever form on the poleward side of them. 
It is obvious, therefore, that spots are not produced by the 
condensation of materials on their upper surfaces, for in that 
case the spots would be produced indifferently on either side of 
them, and the width of the spot-zones would be inordinately 
increased. 
Although in the foregoing I have laid stress upon the indica 
tions afforded by the observations of 1878 of the existence of a 
ring, it snould be remarked that, so far, the eclipse appearances 
Fic. 4.—14 years from maximum, 1858. 
on which the idea rests have not been observed at maximum. 
Tracing of drawing by Liais, 
This, however, is not a fatal objection, because precautions for } 
shielding the eye were necessary even in 1878 when the corona 
was dim ; and if it is composed merely of cooled material it 
would not readily be photographed. 
In may be urged by some that the phenomena observed in 
1878 may only after all have been equatorial streamers. 
It is obvious, therefore, that this point deserves the closest 
etion during future eclipses, until it is settled one way or the 
other. 
Geological Society, June 23.—Prof. J. W. Judd, F.R.S., 
President, in the chair.—The President announced that ae h ad 
received from Prof. Barrois an intimation that the Geological 
Society of France would hold a special country meeting in the 
district of Finistére from the 19th to the 28th of August next, 
during which a variety of interesting excursions would be made 
under’ the guidance of MM. Barris Davy, and Lebesconte. 
Prof. Barrois, i in writing, expressed the pleasure which it would 
give the members of the Geological Society of France if they 
were joined by some of their Eng 1elish confréres, but at the same 
time Stated that as the accommodation for travellers was limited 
in the district, he would be glad to have a notice from any 
One intending to take part in the meeting. Particulars were to 
be obtained from the Assistant Secretary, who would also com- 
municate with Prof. Barrois.—The following communications 
showing “cones.” 
were read :—On some perched blocks and associated pheno- 
mena, by Prof. T. McKenny Hughes, M.A., F.G.S. The 
author described certain groups of boulders which occurred on 
pedestals of limestone rising from 3 to 18 inches above the level 
of the surrounding rock. The surfaces of these pedestals were 
striated in the direction of the main ice-flow of the district, while 
the surrounding lower rock in no case bore traces of glaciation, 
but showed what is known as a weathered surface. He inferred 
that the pedestals were portions of the rock protected by the 
overhanging boulder from the down-pouring rain, which had 
removed the surrounding exposed parts of the surface. When 
the pedestals attained a certain height relatively to the surround- 
ing rock the rain would beat in under the boulder, and thus 
there was a natural limit to their possible height. He referred 
to the action of vegetation in assisting the decomposition of the 
limestone, and considered that there were so many causes of 
different rates of waste and many sources of error, that 
he distrusted any numerical estimate of the time during 
which the surrounding limestone had been pate to denuda- 
tion. Considering the moce of transport of the boulders, 
thought that they could not have been carried by marine currents 
and coast-ice, as they had all travelled, in the direction of the 
furrows on the rock below them, from the parent rock on the 
north. Moreover, marine currents would have destroyed the 
| glaciation the rock and filled the hollows with debris. 
Furthermore, the boulders and strix are found in the same dis- 
so 
he 
