498 



'NATURE 



[March 22, 1894 



run to earth. The remaining article is on the teaching of mathe- 

 matics in the secondary schools (pp. 127-130), and consists of 

 an extract from the report rendered to the National Educa- 

 tional Society, December 1893, by the Committee on Secondary 

 School Studies. 



Meieorologische Zeitschrift, February. — The results of the 

 Swedish International Polar Expedition at Cape Thorsden, 

 Spitzbergen, 1882-83, by Dr. J. Hann. The meteorological 

 results, which have only recently been published, show that the 

 winter temperature is relatively very mild compared with that 

 observed at all the other Polar stations north of 70° N. latitude. 

 In the year commencing September 1882, and ending August 

 1883, Cape Thorsden, latitude 78° 28", had the smallest 

 extreme cold, with the exception of Jan Mayen, latitude 71°, 

 while the summer was very cool. The lowest mean monthly 

 temperature was — 1°'3 in December, and the absolute minimum 

 -3i°*9 in January; the highest mean monthly temperature 

 ■was 40° "S, and the absolute maximum 56^ '5, both in August. 

 The yearly rainfall (including snow), was 7*4 inches; no real 

 hail fell during the year. The daily range of the barometer 

 shows a double period, as in lower latitudes, but the maxima 

 and minima occur at different hours; the day maximum occurs 

 about ih p.m., and the minimum about 6h. a.m., and there is 

 a second maximum from loh. p.m. to midnight, and a second 

 minimum about 6h. p.m. In summer the amplitudes are much 

 smaller than in winter ; the day maximum then occurs from about 

 noon to ih. p.m., and the afternoon minimum about 6h. p.m. 

 The prevalent wind directions are east and west ; in summer 

 the south-west wind is most frequent, and in winter north-west 

 and east. The daily range of wind velocity is very marked in 

 summer, the maximum occurring about ih. p.m., and the 

 minimum about ih. a.m. ; while the reverse obtains in winter, 

 but with less regularity. 



SOCIETIES AND ACADEMIES. 



London. 



Royal Society, March i. — "Terrestrial Refraction in the 

 Western Himalayan Mountains." By General J. T. Walker, 

 C.B.,F.R.S. 



In the operations of the great Trigonometrical Survey of 

 India it is customary to determine the coefficient of refraction 

 by reciprocal vertical observations between contiguous stations 

 on the sides of all the principal triangles, and also as many as 

 possible of the secondary triangles. 



The values of the coefficient thus obtained for the operations 

 in the Western Himalayas — between the meridians of 73° and 

 80° east of Greenwich — have been grouped together for com- 

 parison in successive ranges of 2000 feet of altitude between the 

 elevations of 5000 and 21,000 feet above the sea-level. The 

 operations happen naturally to have been divided into two 

 sections ; for the regions lying between the great snowy ranges 

 on the southern face of the Himalayas and the plains of India 

 were first completed, and some time subsequently the still 

 higher regions to the north, extending up to the Karakoram 

 and Kuenlun Ranges, which look down on the plains of Tur- 

 kestan. The first portion appertains to what is called the N. W. 

 Himalyan Series, the second to what is called the Kashmir 

 Triangulation. Thus the values of the coefficients of refraction 

 were ob'ained separately for each section, and the results show 

 that at each range of altitude the coefficient of refraction was 

 greater in the Southern than in the Northern Section ; also 

 that from the height of 13,000 feet upwards the coefficient de- 

 creased in magnitude, as it theoretically should do, in the 

 Northern Triangulation, but, on the other hand, in the Southern 

 it increased until it became twice as great as in the Northern. 

 These differences of behaviour in the two regions are very 

 curious and difficult to account for. They point to some 

 difference in the atmospheric conditions to the north and 

 south of the outer Himalayan Range, and this may possibly 

 arise from the circumstance that the atmosphere to the south is 

 more heavily laden with moisture than the atmosphere to the 

 north ; for the great southern range is the first to receive the 

 clouds which come up from the Indian Ocean, and which are 

 the chief source of Himalayan moisture ; these clouds are 

 mostly condensed into rain on the southern face of the range, 

 and thus only a comparatively small portion of their contents is 

 carried on beyond into the more northerly regions. Whatever 

 the cause, the fact is very remarkable that the coefficient of 



NO. 1273, VOL. 49 



refraction has a minimum value at an altitude of 20,000 feet on 

 the north side of the Himalayan Ranges, and a maximum value 

 at the same altitude on the south side. 



"On a Spherical Vortex." By Dr. J. M. Hill, Professor of 

 Mathematics at University College, London. 



The nature of the irrotational motion of an infinite mass of 

 frictionless fluid, in which a solid sphere is moving, is well 

 known. The object of this investigation is to show that con- 

 tinuous motion throughout space is possible if the solid sphere 

 be replaced by a spherical mass of rotationally moving fluid. 

 This spherical mass is the spherical vortex of the investigation. 

 Its centre moves with uniform velocity along a straight line, 

 which may be called the axis of the vortex. The surfaces inside 

 the vortex which contain the same particles of fluid throughout 

 the motion are ring-shaped surfaces of revolution about the 

 axis, but are not anchor-rings. The molecular rotation at any 

 point of the vortex is proportional to the distance of the point 

 from the axis. The cyclic constant of the spherical vortex is 

 equal to five times the product of the radius of the sphere and 

 the uniform velocity with which the vortex moves along its 

 axis. 



Dr. E. L. Melius made a preliminary report of the re- 

 sults of experimental investigation of the central nervous 

 system of the monkey {Macacus sinicus) at the patho- 

 logical laboratory of University College. Small portions 

 of the cortex cerebri were removed from the left hemisphere, 

 amounting in each case to about 16 sq. mm. At the end of 

 three weeks the animals were killed, and the resulting degenera- 

 tion traced by Marchi's method. Two foci of representation 

 were selected for excision : the focus for the movements of the 

 hallux, and the focus for the movements of the thumb. In the 

 former, degeneration had taken place extensively throughout 

 the pyramid of the left side down to the decussation in the cer- 

 vical region, where the degenerated fibres were seen to divide, 

 the greater portion, about two-thirds, crossing over to the 

 opposite (right) lateral column, the remainder passing through 

 the grey matter to the lateral column of the left side. This de- 

 generation was maintained throughout the entire cord to the 

 lower lumbar region. In the case of the removal of the thumb 

 centre similar degeneration was observed, though the number of 

 degenerate fibres was less than in the former. At the decussa- 

 tion the tract also divided, though the proportion of fibres going 

 to the left lateral tract was much less than in the case of the 

 hallux, and there was no degeneration of the cord below the 

 level of the second dorsal nerve. 



Mathematical Society, March 8. — Mr. A. B. Kempe, 

 F.R.S., President, in the chair. — The following papers were 

 read : — Groups of points on curves, by Mr. F. S. Macaulay. 

 In the earlier part of the paper a proof is given that any «"'"= 

 through all the points of intersection of two given curves C/, C, 

 of orders / and m is necessarily of the form 



but the chief part of the paper is an investigation of the amount 

 of independence of a group of points on a given curve which 

 are residual to the partial intersection of the given curve by 

 another curve of any order. The ques'ii>n may be expressed 

 thus : — " If three curves C;, C,,, C„(/;|>w^«) have N points 

 common (N being not Ie>s than i/./-f-3), what is the amount of 

 independence of the remaining poin!> common to C , C« (and 

 those common to d, C/) for curvesof any order passin, through 

 them, and what is the number of absolute rtlations that connect 

 either of the above groups of points among themselves ? " The 

 method of investigation is geometrical, i.e. it does noi depend 

 on the solution of any equations or on the investigation of the 

 properties of a curve from its equations. — On a simple con- 

 trivance for compounding elliptic motions, by Mi. G. H. Bryan. 

 The author exhibited a numi er of " pendulum curves " drawn 

 with a very simple arrangement based on the principle of a pen- 

 dulum curve-tracer that ht saw exhil'ited at the British Associa- 

 tion meeting at Nottingham. The paper to be drawn on is 

 placed on a heavily weighted board suspended from 'wo points 

 overhead by strings attached to its four corners in such a v<ay 

 that it can swing in any direction without twisting round. From 

 the under-side of the board is suspended a weight, thus giving 1 

 two periods of oscillation. The pen is attached to a niangular 

 framework, hinged to fixed supports, and carefully counter- 

 poised. The pen thus rests gently on the paper, whicti moves 

 about underneath. The author uses a kind of " reservoir pen, 



