March 8, 19 17] 



NATURE 



39 



>pecially — have been responsible for a great develop- 

 aent of that portion of the alveolar process which 

 lodges the incisor, canine, and premolar teeth. In 

 respect of this feature the Talgai skull is probably 

 more primitive and ape-like than that of any other 

 known specimen belor ging to the human family, 

 excepting only the Piltdown skull, the dental arcade 

 of which that of the Talgai skull, in spite of its 

 immaturity, nearly approaches, not only in actual size, 

 but also in its relative proportions. The fact that 

 the brain-case had already reached the stage repre- 

 sented in the modern Australian aboriginal, while the 

 face still retained much of the grossness and uncouth- 

 •ss of the ape's, is a further confirmation of the 

 iewthat, in the evolution of man, the brain first 

 cquired the human status and the refinement of the 

 atures came afterwards.— Dr. C. Chree : The mag- 

 netic storm of August 22, 19 16. The paper gives an 

 account of a magnetic storm, accompanied by aurora 

 in Scotland, which occurred on August 22-23, 1916. 

 A comparison is made of the results derived from 

 the magnetic curves at Kew and Eskdakmuir Ob- 

 servatories. The disturbance was much larger at the 

 latter station than at the former. During, however, 

 the most disturbed period, both places afforded a con- 

 spicuous example -of the type of storm in which the 

 direction of the disturbance vector shows a rapid 

 rotation. During this period the disturbance vector 

 diagram in the horizontal plane was described con- 

 tinuously in a counter-clockwise direction, nearly a 

 complete revolution being effected in the course of 

 one hour. — Prof. W. H. Yonng : The ordinary con- 

 \ergence of restricted Fourier series. 



Optical Society, February 8.— J, W. French : More 

 notes on glass grinding and polishing. Glass is 

 abraded by splintering, and the efficiency of an abrasive 

 is determined by the form of the grains, their hardness, 

 and their cleavage. A grain that cleaves and presents 

 flat surfaces loses its cut, whereas one that retains its 

 original form when broken suffers only a temporary 

 loss of cut during the grinding process. When pre- 

 cautions are taken to prevent clogging of the abrasive, 

 the amount of glass removed is directly proportional 

 to the relative speed of the grinding tool and the glass. 

 In lubrication too much water has the same bad effect 

 as too little water. A new method was described of 

 comparing the qualities of ground glass surfaces. 

 Polishing was divided into wet polishing, in which 

 material is principally removed, and dry polishing, in 

 which the surface sleeks are filled or closed. A 

 mechanical theory of polishing was elaborated. Rouge 

 consists of grains of ultra-microscopic size. These 

 graips appear to gather, snowball fashion, into lumps 

 of about two wave-lengths diameter, and in this con- 

 dition they plough grooves in the surface layer. 

 During the second stage these grooves are closed up, 

 thus improving the brilliancy of the surface. When 

 a rounded point is drawn heavily over the surface, a 

 series of semicircular cracks is produced. The crack- 

 ing takes place on the tension side, and not on the 

 pressure side; the cohesion of the surface layer is less 

 than that of the underlying material. The diameters 

 of the cracks produced have a definite relationship to 

 the pressure. With the semicircular cracks there are 

 associated two series of tangential cracks. Fire- 

 glazed surfaces and fracture-glazed surfaces give 

 similar results; also polished quartz; but the natural 

 polished surfaces of crystals resulting from crystal 

 growth do not exhibit sleeks or surface cracks, thus 

 suggesting the non-existence of a surface layer. 



Linnean Society, February 15.— Sir David Prain, 

 president, in the chair.— J. H. Owen : The home-life 

 of the sparrow-hawk (Accipiter nisiis, Linn., Pall.). 



NO. 2471, VOL. 99] 



After a brief description of the life of the birds from 

 autumn to spring, an account was given of the nest- 

 ing habits, from the selection of the nesting site in 

 March to the scattering of the young at the end of 

 July or in the early part of .August. A series of 

 lantern-slides was exhibited to illustrate various 

 features of the nesting habits and growth of the 

 young. Of these, particular interest attached to a 

 series showing the various methods of brooding ' in 

 wet weather and the care taken over the welfare of 

 the youngest nestling. Another series showed the 

 young able to feed themselves, while the hen keeps 

 watch above the nest during the course of the meal 

 until the young are all asleep after the food is finished. 

 Slides were shown of the visits of young and the 

 old birds to the nest after the young had left. 



Royal Microscopical Society, February 21. Mr. E. 



Heron-.Allen, president, In the chair. — Drs. A. H. 

 Drew and Una Griffin : The parasitology- of Pyorrhoea 

 alveolaris. The authors stated that careful micro- 

 scopic examination of material from cases of pvorrhoea 

 showed that, in the great majority of cases, at least 

 two species of Amoebae were present. One of these 

 Amoebae appeared to be a semi-parasite partially modi- 

 fied by anaerobic life in the pockets around the teeth. 

 When stained by the iron-haematoxylin m.ethod, this 

 form showed a valkamfia type of nucleus; it also pos- 

 sessed a flagellate phase in its life-cycle. The name 

 Amoeba biiccalis was proposed for this type, which 

 had been successfully cultivated, after concentration 

 of the cysts by Dr. Cropper's method. The other 

 species was a true Entamoeba, and corresponded to 

 Entamoeba gingivalis. Two new flagellates had been 

 found in the pockets, together with at least six species 

 of spirochaetes. 



Mathematical Society, March i. — Mr. G. H. Hardy, 

 vice-president, in the chair. — A. E. Jollifle : Some 

 properties of a quadrangle formed by the points of 

 contact of the tangents drawn to a nodal cubic from 

 any point. — E. H. Neville : Indicatrices of cur\-ature. 



Paris. 

 Academy of Sciences, January 15.^ — M. d'Arsonval in 

 the chair.— G Bigoardan : The first scientific societies 

 of Paris in the seventeenth century. — E. Aries : The 

 law of molecular entropy of fluids taken at correspond- 

 ing states. The application of the equation of state 

 deduced in an earlier paper. — W. Kilian and J. Revil : 

 The history of the .Arc valley at the Pleistocene period. 

 — A. Khintchine : Asymptotic differentiation. — H. 

 Arctowski : The heliographic positions of the sun-spots 

 and magnetic storms. .After a historical summary of 

 the previous work on this subject the author especially 

 examines the hyootheses of Veeder, Ricco, and Terby. 

 Using data for magnetic storms from observaticwis 

 made at Porto Rico and Greenwich, and Greenw-ich 

 figures for sun-spot areas, the conclusion is drawn that 

 Veeder's hypothesis is completely out of accord with 

 the observed facts. Terby 's hypothesis is equally 

 faulty, but the views of Ricco are partially verified. — 

 J. Deprat : The Ordovician and Gothlandian in the 

 north of Tonkin and the basin of the upper lou-Kiang. 

 — M. Raclot : The origin of terrestrial magnetism. As- 

 suming that the intTrrnal mass of the eatth' consists of 

 an alloy in which iron predominates, then, on account 

 of the high temperature, the iron under the continents 

 would be above the critical point at which magnetic 

 properties disappear (750° C. to 900° C). Under the 

 oceans, on the contrary, by reason of the m-^re rapid 

 coolinp^ assumed bv Faye, the superficial layer could 

 have arrived at a temperature below 750° C, and, in 

 consequence, a certain thickness of this could be mag- 

 netic. Wulde has shown that if a globe is covered 



