futie 5, i 884 J 



NATURE 



'39 



The tables show that both for light polarised in and perpen- 

 dicularly to the plane of incidence the observed intensity exceeds 

 the calculated intensity, in the former case by about I, and in 

 the latter by about 2 per cent., except at incidences of 30° with 

 light polarised in the plane, and 70° and 75° for light polarised 

 perpendicularly to the plane, for which angles the observed and 

 calculated intensities agree closely. 



These results appear to confirm the general conclusion arrived 

 at in the former paper, that, although the received formulae for 

 metallic reflection are approximately correct, they are not a com- 

 plete expression of the facts of the case. 



Zoological Society, May 20. — Sir Joseph Fayrer, F.R.S. 

 vice-president, in the chair. — Mr. W. T. Blanford. F.R.S., 

 exhibited and made remarks on a series of horns of the Wild 

 Sheep of the Pamir, Ovis polii, Blyth, which had been obtained 

 by the lion. Charles A. Ellis, F.Z.S., from the Pamir district 

 during his recent journey to Yarkand. — Mr. R. Bowdler Sharpe 

 exhibited and made remarks on a second specimen of the new- 

 European Nuthatch (Sitia whitehead!) recently discovered by 

 Mr. Whitehead in Corsica. — Dr. J. G. Garson exhibited and 

 made remarks upon a specimen of Lithodes main, the Northern 

 Stone-Crab. — Mr. Frank E. Beddard, F.Z. S., read the first of 

 a series of papers on the Isopoda collected during the voyage of 

 H.M.S. Challenger. The present communication treated of the 

 genus Serolis, sixteen species of which were represented in the 

 specimens obtained during the expedition. Of these nine were 

 described as new. The author also gave a short account of the 

 geographical distribution of the genus, and pointed out some of 

 its peculiar structural points. — Mr. Gwyn Jeffreys, F.R.S., read 

 the eighth part of his papers on the Mollusca of the Lightning 

 and Porcupine Expeditions. It included the families Aclidse, 

 Pyramidellida?, and Eulimidse, with seventy-five species. Two 

 genera and twenty-three species were described by the author as 

 new to science. — Prof. Jeffrey Bell read the fourth of his series 

 of papers on the Holothurians. The present communication 

 gave an account of the structural characters of the Cotton-Spinner 

 \Holothuria nigra), and especially of its Cuvierian organs. — Mr. 

 F. Day read a paper on races and hybrids among the Salmonid.e. 

 in continuation of a former communication made to the Society, 

 and continuing an account of the experiments made by Sir James 

 ( iibson-Maitland in the hybridisation of Salmonidre in the ponds 

 at Howietown. — A communication was read from Mr. R. Collett, 

 C.M.Z.S., containing the description of some apparently new 

 Marsupials obtained by Dr. Limholtz in Northern Queensland. 

 These were described as Phalangisla areheri, Ph. herbertensis, 

 Ph. Itmuroides, and Deiidrolagus Umholtzi. 



Geological Society, May 14.— Prof. T. G. Bonney, F.R.S. , 

 president, in the chair. — John Ruscoe was elected a Fellow of 

 tire Society. — The following communications were read : — On 

 the pre-Cambrian rocks of Pembrokeshire, with especial refer- 

 ence to the St. David's district, by Dr. Henry Hicks, F.G. S., 

 with an appendix by Thomas Davies, F. G. S. The author in 

 this paper gave further detailed evidence in addition to that 

 already submitted by him, to show that the Geological Survey 

 Map of the district of St. David's and of other parts of Pem- 

 brokeshire is incorrect in some of its most essential features, and 

 inaccurate in very many of its petrographical and stratigraphical 

 details. Some new areas in South Pembrokeshire were also 

 referred to. He replied also to the criticisms contained in the 

 paper by the Director-General of the Survey, read last year 

 before the Society, and indicated that Dr. Geikie had completely 

 misunderstood the sections and the order of succession of the 

 rocks at St. David's. He pointed out that the views so elabor- 

 ately worked out by the Director-General to show the evidence 

 of metamorphism in the rocks, were based on the entirely false 

 supposition that the granitoid rocks were intrusive in the Cam- 

 brian rocks, and that the felsites were merely peripheral masses. 

 He showed, by producing abundant fragments of the granitoid 

 rocks and of the felsites from the basal Cambrian conglomerates, 

 that the granitoid rocks were the very oldest rocks in the district, 

 and that they must undoubtedly be of pre-Cambrian age. He 

 proved, from microscopical evidence, that the rocks supposed to 

 have been altered by the intrusion of the granitoid rocks, were 

 in the condition in which they are now found before the Cam- 

 brian rocks were deposited, and, moreover, that the supposed 

 concretions in the porcellanites and conglomerates, claimed to 

 have been due to metamorphism, had turned out, on microscopi 

 cal evidence, to be actually fragments of old pre-Cambrian 

 rhyolites inclosed in the sediments. It was shown also that at 

 the points indicated by the Director-General, where the evidences 



of intrusion were supposed to be seen, there was not the slightest 

 change of a metamorphic character induced in the sedimentary 

 rocks in contact with the granitoid rocks. The only difference 

 that could possibly be recognised in them by the aid of the 

 microscope was such as is well known to be the result of crush- 

 ing when in the neighbourhood of faults. Indeed there was the 

 clearest evidence possible to show that the junctions were merely 

 fault junctions. The supposed fold in the Pebidian rocks, the 

 author stated, was impossible if petrological evidence was of any 

 value. The author also produced many facts to show that the 

 conglomerates at the base of the Cambrian constantly overlapped 

 the different members of the series which he claimed to be of 

 pre-Cambrian age, and that the unconformity was very marked 

 and to be clearly seen in many coast sections. The conglomer- 

 ates were shown also to contain well-rolled pebbles of all the 

 series included under the names Dimetian, Arvonian, and 

 Pebidian, as proved by careful microscopical examination of the 

 fragments by Mr. T. Davies and himself. An appendix by Mr. 

 Davies, describing the microscopic character of the rocks, accom- 

 panied the paper. — Note on a specimen of iron amianthus, by 

 the Rev. J. Magens Mello, M.A., F.G.S. The accompanying 

 specimen was found at the bottom of one of the Wingeworth iron- 

 furnaces, near Chesterfield, and was given to the author by Mr. 

 Arthur Carrington, one of the owners. The furnaces have been 

 lately blown out for repairs, and in the mass of slaggy refuse at 

 the bottom a thin layer of the curious product known as iron 

 amianthus was interposed between the sand and the iron refuse. 

 The red sand at the bottom of the furnace was converted in its 

 upper part into a compact, hard, white sandstone an inch or two 

 in thickness, and upon the top of this the iron amianthus oc 

 curred in snow-white fibrous masses, the fibres radiating in a 

 concentric manner, and forming more or less botryoidal concre- 

 tions, somewhat resembling haematite in appearance, and separ- 

 ated by extremely thin plates or septa of iron, by which the 

 entire mass is divided into irregular prisms of about half an inch 

 in diameter. 



Physical Society, May 24. — New member, Mr. F. C. 

 Phillips, electric engineer. — Prof. W. G. Adams took the chair 

 while the President, Dr. Guthrie, gave a brief summary of his 

 recent researches on eutectic alloys, that is alloys of low fusing 

 point. The complete research will be published in the Society's 

 Proceedings. Dr. Guthrie showed by means of tables and curves 

 of results that mixtures of water and nitre, nitre and nitrates, 

 &c, behaved in the same way as fusible alloys, such as alloys of 

 lead and bismuth. On cooling down the alloy or mixture, the 

 ingredient present in richer quantity crystallised out. There 

 seemed to be no definite molecular proportions in these alloys. 

 A " tetra-eutectic " alloy of bismuth 47'3$, tin IQ'97, lead I9'36, 

 cadmium I3'2a per cent., was exhibited by the author, which 

 fused at 71°, or in boiling alcohol. Rose's fusible metal melts at 

 93°. Results were given of the behaviour of mixtures of water 

 and the aniline salts, salicylate, oxalate, &c. ; also of water and 

 tri-ethylamine, and other members of the ammonia group. Dr. 

 Guthrie's observations tended to show that fusion ard solution 

 were of the same nature. He pointed out their bearing on 

 mineralogy and geology, and inferred that water in igneous rocks 

 was there from the first, and not by infiltration, as some suppose. 

 — The President then took the chair, and Dr. W. H. Stone 

 exhibited a simple, cheap, and portable galvanometer for hospital 

 use, made of a boxwood cylinder with coils wound round it, and 

 a needle with mirror, inserted into a test-tube, and pushed into 

 the hollow of the cylinder. The needle is made dead-beat by 

 putting paraffin oil into the tube. He also exhibited a Kohlrausch 

 metre bridge for alternating currents, a telephone playing the 

 part of indicator. Dr. Stone employs it for measuring the resist- 

 ance of the human body, which he finds to be less than 1000 

 ohms. With high-tension currents it appears lower than with 

 low-tension currents. Another metre bridge of the kind with a 

 longer wire (3 m. in this case as compared with |m. in the other) 

 was also shown in connection with a sledge induction-coil, by which 

 the power of the current can be regulated to suit the patient. Dr. 

 Stone stated that the body acts more like a solid than a liquid 

 conductor. Mr. Glazebrook said he had used a similar plan 

 with a telephone to measure the resistance of electrolytes ; but 

 found the telephone too sensitive from induction, though in Dr. 

 Stone's work this objection might not apply. Prof. G. Forbes 

 stated that the telephone had been applied in a similar way to 

 comparing capacities. With regard to the danger from currents, 

 Prof. Ayrton said the E.M.F. of the railway current at Bush- 

 mills was 250 volts, and pointed out that very intermittent currents 



