October 6, 1898] 



NATURE 



559 



formation. Sir John Evans called attention to the fact that in 

 one section in Belgium, where the Palceozoic strata were ex- 

 tremely folded, Coal Measures'had been met with beneath a 

 M'edge of Old Red Sandstone. Mr. E. Wethered suggested that 

 the Coal Measures showed a tendency to become less and less 

 productive when traced eastward from the South Wales basin ; 

 and Prof. Louis asked how the supposed horizontality of the 

 Dover Coal Measures could be explained, while in their sup- 

 posed prolongation in Belgium they were so greatly disturbed. 

 Mr. Etheridge, in concluding the discussion, thought there 

 could be no doubt that the bottom rock at Brabourne was Old 

 IVed Sandstone, and remarked on the evidence now forth- 

 coming for the continuous underground extension of this form- 

 ation from Bristol across the south of England, under London 

 and parts of Kent, into Belgium. 



The next paper was that of Dr. Marsden Manson, of Sacra- 

 mento, Cal., on "The laws of climatic evolution" — a highly 

 speculative attempt to explain the Glacial Period as a critical 

 and unique stage in the evolution of this and other planets when 

 the ;climate passed from "internal" to "external" control. 

 According to Dr. Manson, the climatal conditions of all times 

 preceding the Glacial Period were determined by planetary heat, 

 and were independent of latitude ; but the dissipation of the 

 continuous cloud-envelope, through the loss of the planetary 

 heat by which it had been sustained, brought about a new set of 

 conditions. After a Glacial Period, due to the more rapid cool- 

 ing of the land than the sea, a gradual rise of temperature along 

 with a zonal distribution of climate would occur, through the 

 trapping of solar heat by the lower layers of the atmosphere. 

 This latest of the many ingenious attempts which have been 

 made, on both sides of the Atlantic, to explain the Glacial 

 Period was admirably presented by the author to a large 

 audience, but was subjected to severe criticism in the dis- 

 cussion, the general feeling being that such speculations 

 scarcely fell within the scope of Section C. 



Prof. E. Hull brought before the meeting a wide subject 

 of more tangible character, in a paper on "The sub-oceanic 

 physical features of the North Atlantic." By tracing out the 

 depth-contours of the Admiralty Charts, Prof. Hull showed 

 that the British and continental submarine platform breaks off 

 abruptly in a "Grand Escarpment" at depths varying from lOO 

 to 250 fathoms. This escarpment, from 6000 to 7000 feet high, 

 is, according to Prof. Hull, indented by deep bays and old 

 river-channels, the latter, almost caiion-like in places, often 

 prolongations of the river valleys of the existing land. These 

 and other submarine features lead him to agree with Spencer and 

 Upham that the whole area of the North Atlantic to a depth of 

 10,000 feet was a land surface at a very recent period, and that 

 the conditions of the Glacial Epoch may be thus explained. 

 This paper was followed by another on the same subject by 

 the President of the Section, in which it was shown that the 

 exaggeration of the vertical scale made Prof. Hull's diagrams 

 iiisleading as to the slopes of the supposed escarpments and 

 -ubmerged river-valleys ; and evidence was adduced to prove 

 that extensive earth-movements were frequently in progress on 

 the edge of the continental platform. Hence, it was urged, the 

 features to which Prof. Hull had called attention might possiblv 

 be due to subterranean causes, a view which was shared by 

 several speakers in the subsequent debate. 



On the subject of earth-movement. Prof. J, Milne presented 

 the report of the Committee for Seismological Investigation ; 

 and Mr. R D. Oldham, of the Geological Survey of India, 

 i^ave a lucid description, illustrated by lantern slides, of the 

 < ireat Indian Earthquake of 1897. The surface indications of 

 lulting and overthrusting which characterised this earthquake 

 A ere very clearly demonstrated. 

 At the opening of Tuesday's meeting the President, in ex- 

 i biting a portrait of the late E. Wilson, referred feelingly to 

 ihe loss which geological science had sustained by Mr. Wilson's 

 untimely death, and other speakers bore testimony to his pains- 

 taking and self-denying services to the Bristol Museum. 



On behalf of Prof. H. F. Osborn, who had expected to 



tend the meeting but was at the last moment prevented, an 



\hibit was made of some beautiful water-colour drawings of 



•storations of Bronlosaurus, Phenacodtis, and other extinct 



.rtebrates, executed by Mr. C. Knight for the Museum of 



Natural History of New York. A brisk discussion sprang up, 



Ml which Prof. H. G. Seeley, Prof. O. C. Marsh, Sir John 



llvans, Prof. W. Boyd Dawkins, Prof. W. J. Sollas, and others 



look part, as to the advisableness of giving reins to the imagin- 



NO. I 5 10, VOL. 58] 



ation in the production of these restorations, upon which point 

 widely diverse opinions were expressed. 



There was scarcely sufficient time at this meeting to do justice 

 to the carefully prepared p)aper by Mr. W. H. Wheeler on 

 " The action of waves and tides on the movement of material 

 on the Sea-coast." It was shown by Mr. Wheeler that the 

 travel of shingle is not usually coincident with the prevailing 

 winds, but is in the direction of the flood-tide, and is mainly 

 due to wavelets set up by tidal action, whose total kinetic 

 energy is very large. 



Among the other papers brought before the Section were the 

 following on cave exploration : by Mr. H. Bolton and the late 

 E. Wilson, on the exploration of two caves at Uphill, Weston- 

 super-Mare ; by Rev. G. C. H. Pollen, on further exploration 

 of the the Ty Newydd Caves ; by Mr. T. Plunkett, on further 

 exploration of the Fermanagh Caves : and the Report of the 

 Committee on the fauna of caves near Singapore. Mr. P. M. 

 C. Kermode, in the Report of the Committee for investigating 

 the mode of occurrence of the Irish Elk in the Isle of Man, 

 announced the discovery of a large and nearly complete skeleton 

 of that animal near Peel. Mr. J. Lomas brought forward 

 evidence in favour of the occurrence of worked flints in the 

 Glacial deposits of Cheshire and the Isle of Man, but it was felt 

 that further research was necessary before the author could be 

 considered to have established his case. Mr. C. W. Andrews 

 gave an account of the discovery of a portion of the skeleton of 

 a huge Dinosaur in the Oxford Clay of Northampton. Papers 

 were also contributed by Mr. J. R. Dakyns on the probable 

 source of the upper Felsitic lava of Snowdon ; by Mr. H. B. 

 Woodward on arborescent Carboniferous Limestone from near 

 Bristol ; and by Mr. W. L. Addison and Mr. L. J. Spencer on 

 crystallographic and mineralogical subjects. Several of the 

 Reports of Committees possessed matter of much interest, 

 especially that presented by Prof. A. P. Coleman on the Inter- 

 glacial deposits near Toronto (where fresh facts of importance 

 have been gained by excavations), and that of Prof. P. F. 

 Kendall on Erratic Blocks ; while the Conmiittee for collecting 

 Geological Photographs, that on Fossil Phyllopoda, and that on 

 Life-zones in British Carboniferous rocks were all able to report 

 steady progress in their investigations. New committees were 

 formed and grants obtained to investigate the caves at Uphill 

 and at Ty Newydd, and as already mentioned to preserve 

 photographic and other records of the Moel Tryfaen section ; 

 and most of the old committees connected with this Section 

 were re-appointed. 



PHOSPHORESCENCE.'^ 



T T is not possible in one lecture on phosphorescence to give 

 -"■ any historical sketch which shall do justice to the work of 

 those who have made a study of the phenomena. In a list of 

 the names of the many who have enriched the subject with facts 

 and with theories, those of Becquerel, of Stokes, and of Crookes 

 stand out most prominently. Any attempt to make a sketch of 

 our knowledge of phosphorescence and fluorescence must be to 

 a very large extent an adaptation of the work and of the views 

 of these masters. 



The phenomena themselves may be divided into two main 

 classes— those in which the evolution of light is associated with 

 chemical change, and those in which there is no evidence of 

 such direct alteration. In the first class the commonest instances 

 are connected with the process of oxidation. Examples of this 

 kind are numerous. It is hardly possible to take any very 

 easily oxidisable substance and to fail to get some evolution of 

 light. Phosphorus, sodium and potassium, ether, many 

 aldehydes, and a host of organic compounds may be cited as 

 instances. The experimental illustrations of these are not, 

 however, suited to an audience of more than a very few. The 

 same may be said of the examples of animal and vegetable 

 phosphorescence. It is proposed, therefore, to deal more 

 especially with the second class, and to limit the experiments to 

 the cases where the light given out is visible and not of such a 

 character as to necessitate the use of a photographic plate. This 

 evolution of light may occur in varying conditions. In instances 

 such as solutions of quinine and fluorescein and many solids, of 

 which thallene is a good example, the duration of the phos- 

 phorescence is so short that it may be said to last only while 



1 \ discourse delivered before the British .Association on September 12, 

 by Mr. Herbert Jackson. 



