-':)< 



NATURE 



[November 29, 191 7 



the north (9903 ft,). The southern wall only reaches 

 the height of 9434 ft. The crater-wall has slipped 

 down on the south-west to form a narrow shelf. The 

 crater is nearly circular, and the lowest points lie on 

 the long axis.' The crater-wall has an external slope 

 of 33° on the south and east. The history of the 

 volcano may be summarised thus: — (i) 'Its forerunner 

 was the Kerkur Dagh on its southern flank — a denuded 

 mass of grey augite-trachyte. It was .probably erupted 

 in the Pliocene period, following the folding of 

 the Armenian area, in which the latest folded rocks 

 are of Miocene (Helvetian-Tortonian) age, consisting 

 of limestones with corals and ovsters. It came into 

 existence at a period when the sedimentary rocks could 

 no longer be folded, but were fractured along definite 

 lines, and Nimrud is situated on the great fracture 

 transverse .to the Armenian folds at the apex of their 

 bending round from the Antitauric to the Persian 

 direction. (2) Numerous flows of augite-rhyolite built 

 up the vast cone of the Nimrud Dagh, and the 

 increasing pressure on the central vent became relieved 

 bv extrusions of augite-traohyte along radial fissures. 

 (3) A presumably long period of inactivity was followed 

 by violent explosions destroying the summit of the 

 cone, and from this crater vast lava-flows of a fluid 

 basalt flooded the country and filled up the valleys, 

 which have since then been eroded a little below their 

 former depth. (4) Further explosions widened the 

 crater, in which a large lake was formed, while the 

 eastern half of the crater became filled by a succession 

 of outflows of augite-rhyolite. (5) The last eruption 

 was recorded in 1441 by a contemporary chronicler, 

 and resulted in the extrusion of a viscous augite- 

 rhyolite along a north-to-south zone of weakness, both 

 inside the Nimrud crater and also to the north. (6) 

 A violent earthquake in 1881, which destroyed the 

 village of Teghurt, was the last sign of activity ; but 

 earthquakes are still frequent in the Plain of Mush, 

 and recent fault-scarps are visible along the borders 

 of this faulted depression. Dr. Oswald has presented 

 his model of the crater to the Museum of Practical 

 Geology, and the rocks and slides to the British 

 Museum, where his fossils from Armenia are pre- 

 served. 



Physical Society, November 9.— Prof. C. V. Boys, 

 president, in the chair. — C. R. Darling and A. W. 

 Grace : The thermo-electric properties of fused metals. 

 In a previous paper ("Proceedings," vol. xxix., part i.) 

 the authors described experiments with bismuth, the 

 apparatus then used only being capable of furnishing 

 readings up to 560° C. ^ Methods have now been de- 

 vised in which the metals examined may be heated 

 in the tube of an electric furnace, and observations 

 made up to the temperature limit of the furnace. 

 The metals experimented with were dead, tin, and 

 antimony up to 1000? C, and zinc and cadmium up 

 to temperatures approaching the boiling point. No 

 change in thermo-electric properties was noticed at 

 fusion, except in the case of antimony, which, like 

 bismuth, shows an abrupt bend in the E.M.F. -tempera- 

 ture curve at the melting point, 632° C. This excep- 

 tional behaviour of antimony and bismuth is in keeping 

 with the anomalous properties of these metals, both 

 of which expand on solidification ; and it is suggested 

 that an allotropic change occurs at fusion in these 

 metals. In the case of lead, which is used as the refer- 

 ence metal in thermo-electric diagrams, it is shown 

 that extrapolation of lines in the diagram beyond 300° 

 led to serious errors, and that although at low tem- 

 peratures the E.M.F. -temperature curves are approxi- 

 mate parabolas, the departure from this shape above 

 300° is so marked as to render thermo-electric dia- 

 grams of little value.— T. Smith and Miss A. B. Dale : 

 Triple cemented telescope objectives. The paper de- 

 NO. 2509, VOL. 100] 



scribes the four series of triple cemented thin telescope 

 objectives which can be made from two kinds of glass, 

 and determines their construction when first-order 

 spherical aberration and coma are eliminated. The 

 second-order spherical aberration and coma are then 

 calculated, and the fornier found to be of the same 

 sign for all optical glasses when the surfaces are 

 spherical. The best standard attainable varies very 

 little over a considerable range of glasses. Diagrams 

 show the variations in the curvatures as the glasses 

 are varied for refractive index and dispersion. Con- 

 trary to the general belief, it is found that the objec- 

 tives with least second-order aberrations (absolute 

 values) are not those with the leasit curvatures for their 

 refracting surfaces. 



Linnean Society, November 15. — Sir David Prain, 

 president, in the chair. — Dr. D. H. Scott : Notes on 

 Calamopitys, Unger. Calamopitys is a genus of fossil 

 plants, with structure preserved, of Lower Carbon- 

 iferous age ; some species may perhaps go back to the 

 Upper Devonian. The first part of the paper deals 

 with the origin arid division of the leaf-trace in C. 

 americana. The relations of the five known species 

 among themselves, and of the genus as a whole, are 

 then considered. 



Aristotelian Society, November 19. — Dr. H. Wildon 

 Carr, president, in the chair.- — Mrs. K, Stephen : 

 Thought and intuition. An attempt to bring out the 

 meaning of Bergson's theory of knowledge. Bergson 

 confines his attention to knowledge of existence, and 

 maintains that the best way of knowing existence is 

 to be directly acquainted with it. Thought, which can 

 only give knowledge about, is, according to him, a 

 pis alter, and he only deals with it so far as it affects 

 the actual experience which we get by acquaintance. 

 Thought and acquaintance defeat one another. Never- 

 theless, in practice we try to carry on both operations 

 together, and the result is our everyday experience of 

 things having qualities and relations. This experience 

 is a hybrid product. It still has some of the content 

 of the original act of intuition, but whatever f-ould 

 not be used as material for thought has been left out 

 of it, and it has borrowed the form which belongs to 

 the symbols used by thought. It has been "intellec- 

 tualised." As a new philosophical method, Bergson 

 proposes that instead of limiting our attention to just 

 so much of experience as provides material for thought, 

 and instead of intellectualising our experience, we 

 reverse our mental habits, make an eff'ort to enlarge 

 rather than to limit the whole field of experience with 

 which intuition acquaints us, and attend to it directly 

 without any intermediary. 



Royal Meteorological Society, November 21. — Major 

 H. G. Lyons, president, in the chair. — Dr. G. C. 

 Simpson : The twelve-hourly barometer oscillation, (i) 

 The existence of the twelve-hourly atmospheric vibra- 

 tions, one parallel to the circles of latitude and the 

 other parallel to the meridians, first suggested by A. 

 Schmidt in 1890. and investigated by E. Alt in 1909, 

 has been proved. (2) A mathematical expression for 

 the amplitude and phase of each vibration containing 

 the geographical position as the only variable has been 

 obtained. (3) The interference of these two waves 

 has been shown to account very completely for the 

 observed variations in amplitude and phase of the 

 twelve-hourly barometer oscillations, especially in high 

 northern latitudes. — W. W. Bryant : Abnormal tem- 

 perature, with special leference to the daily maximum 

 air temperature at Greenwich. The author proposes 

 that for certain meteorological elements a value shall 

 be defined as "abnormal" if the departure from a 

 well-established normal is at least twice the mean 

 residual, both normal and residual being determined 



