94 



NA TURE 



[November 23, 189^ 



small conlraction of liquids on cooling did not support this 

 view. — An instrument iox drawing conic sections was exhibited 

 and described by Mr. J. Gillett. This consists of a spindle 

 inclined to a plane board, and a tube fixed to the spindle at an 

 angle. A pencil which passes through the tube traces out a 

 cone in space as the spindle is turned, and on sliding the 

 pencil through the tube, so as lo keep its point against the 

 p'ane, the point traces out a conic, the section ol the cone 

 made by the plane of the board. A circle, ellipse, parabola, 

 or hyperb(<la, can be drawn according to the inclination of the 

 spindle to the board. Prof. Ilenrici said a similar instrument had 

 been 'ilescrihed in an Arabian manuscript a thousand years old, 

 and Has been independently re invented by both a Geiinan and 

 an Italian mathematician. lie thought the fact of the angle 

 between the spindle and the tube in Mr. Gillett's instrument not 

 being adjustable was a disadvantage. Mr. Inwards and Prof. 

 Herschell also took part in the discussion, to which Mr. Gillett 

 replied. 



Geological Society, November 8. — W. H. Iludleston, 

 F.R.S., Fresidt-nt, in the chair. — The following communica- 

 tions were read : — The geology of Baihurst, New South Wales, 

 by W. J. Clunits Ross. After sketching the physiography of 

 the Bailiur,>-t district, the author described in detail its strati- 

 graphy. The oldest sedimentary rocks are Silurian, but the 

 floor on which they rest is unknown, and the author stated that 

 it was probai ly fufed up and incorporated in the granite, which 

 is descri ed in the paper. The Silurian rocks may have been 

 folded before il.e granite was erupted ; in any case, the granite 

 produced a zone of contactmelamorphism, whilst almost all the 

 Silurian n cks may be considered to be examples of regional 

 mtlam(ir|.hism, though the agents producing the metamorphism 

 were least active to the east of Baihurst, where the Silurian 

 limestones are very little altered. An anticlinal was probably 

 produced at the time of the granitic intrusion. After a time 

 there was subside nee, but at first it need not have been very ex- 

 tensive, since the Devonian conglomerates, sandstones, and 

 shelly limestones were probably deposited in a comparatively 

 shallow sea. They contain Lepidodeudron anstrale. At Rydal 

 they al ui against the uplifted Silurian rocks of the Bathurst 

 area. At ihe end of Devonian times there appears to have 

 been a long interval, during which both Silurian and Devonian 

 rocks weie greatly denuded, and the granite exposed in idaces. 

 The Upper Carboniferous and Permian rocks were deposited in 

 the Liihgow district, but it is doubtful if they ever extended to 

 Bathurst. There is nothing to show what happened in this 

 region during Mesozoic and early Tertiary times. The Hawkes- 

 bury Sandstone (probably Triassic) may have approached 

 nearer to Bathurst than it does now. In late Tertiary tiuies 

 stream-deposits were formed on the granitic rocks, and after- 

 wards covered with thick basaltic lava-flows, which have since 

 undergone much denudation. A discussion followed, in which 

 the Pres dem, the Rev. H. H. Winwood, and Mr. J. E. Marr 

 look pait. — Thegfology of Matte Grosso(particularly of the region 

 drained by the Upper Paraguay), by Dr. J. W. Evans. The 

 district includes a portion of the Brazilian hill country, and also 

 of the low-l}ing plains to the south-west The rocks principally 

 dealt with are unfossiliferous, and of unknown age, except that 

 they appear to be older than the Devonian. They may be 

 classified as follows :— (5) Matto Shales (relations not shown) ; 

 (4) Rizama Sandstone (perhaps some unconformity) ; (3) 

 •Curumba and Arara Limestones (very marked unconformity) ; 

 (2) Cuyaba Slates (strong unconformity); (i) ancient crystal- 

 line rocks. The Devonian and later rocks were briefly described. 

 The President, Mr. Spencer Moore, fellow-traveller with Dr. 

 Evans in Matto Grosso, Mr. H. Bauerman, and Mr. K. D. 

 Oldham spoke on the subject of the paper. — Notes on the oc- 

 currence of mammoth-remains in the Yukon district of Canada 

 and in Alaska, by Dr. George M. Dawson, C.M.G., F.R.S. 

 In this paper various recorded occurrences of mammoth-remains 

 were noted and discussed. The remains are abundant in, if 

 not strictly confined to, the limits of a great unglaciated area in 

 the north western part of the North American continent ; whiLt 

 within the area which was covered by the great ice-mass which 

 the author has described as the Cordilleran glacier, remains of 

 the manimoth are either entirely wanting or are very scarce. 

 At the time of the existence of the mammoth the North Ameri- 

 can and Asiatic land was continuous ; for an elevation of the 

 land sufficient to enable the mammoth to reach those islands of 

 the Bering Sea, where these bones have been found, would result 

 in the obliteration of Bering Straits. The bones occur, along 



the northern coast of Alaska, in a layer of clay resting on the 

 somewhat impure " ground-ice formation " which gives indica- 

 tions of stratification; anel above the clay is a peaty layer. The 

 author c>nsidered this " giound-ice ' was formed as a deposit 

 when more continental conditions prevailed, by snow I'all on a 

 region \\ithout the slopes necessary to produce moving glaciers. 

 The inammoth may be supposed to have passed between Asia " 

 and America at this time. At a later date, when Bering Straits 

 were opened and the perennial accumulation of snow ceased on 

 the lou lands, the clay was probably carried down from the 

 highlands and deposited during the overflow of rivers. Over 

 this land the mammoth roamed, and wherever local areas of 

 decay of ice arose bogs would be produced which served a. 

 veritable sink traps. The author considered it probable that 

 the accumulation of "ground-ice" was coincident with \\\t 

 second (and latest) epoch of maximum glaciation, which was 

 followed by an important subsidence in British Columbia. In 

 the discussion of the paper. Sir Henry Howorth remarked upon 

 the long and careful survey of North- West Ameiica which has 

 been made by the author, and upon the value of the conclusions 

 which he has come to: firstly, in legarel to the absence of 

 ancient glaciation in Alaska and its borders ; secondly, in 

 regard to the existence of a great glacier in the Cordilleras, 

 whose products are quite independent of and have nothing to 

 do with the Laurentian drift; and thirdly, in regard to the dis- 

 tribution of I he mammoth. It was a new fact to him, and one 

 of great importance, that mammoth-remains had occurred in 

 Unalashka and the Pribilof Islands in Beriig .Straits, proving 

 that in the Mammoth age there was a land bridge here, ai 

 many inquiiers had argued. It would be very interesting to 

 have the western frontier defined where the mammoth-remains 

 cease to lie found. It would be very interesting to know how far 

 south on the west of the Cordilleras the true mammolh, as dis- 

 tinguished from Elephas Columbi, has occurred. Regarding 

 one conclusion of Dr. DawsonV, Sir Henry could not agree with 

 him, namely, about the age of the strata of ice sometimes 

 found under the mammoth-beds in Ala'-ka as they have been 

 found in Siberia. The speaker was of opinion that this ice had 

 accumulated since the beds were laid down, and was not there 

 when the mammoth roamed about in the forests where he and 

 his companions lived. Humus and soil cannot accumulate 

 upon ice except as a moraine, and there are no traces of 

 moraines or of great surfaceglaciation in Alaska and Siberia. 

 Nor could either the flora or fauna of the memmoth age have 

 survivid conditions consistent with the accumulation of these 

 beds of ice almost immediately below the surface, or consistent 

 with their presence there. The speaker considered that these 

 beds were due to the filtration of water in the summer down to 

 the point where there is a stratum of frozen soil, through which 

 it cannot pass and where it consequently accumulates, freezes, 

 raises the ground, and in the next season grows by the same 

 process until a thick bed of ice has been formed. The evidence 

 goes to show that the present is the coldest period known in 

 recent geological times in Siberia and Alaska, and that the 

 period of the mammoth and its companions was followed and 

 not preceded by an Arctic climate where its remains occur. Dr. 

 H. Woodward remarked that the most interesting point in Dr. 

 Dawson's paper was the mention of the remains of mammoth 

 on the Aleutian Islands, proving that this was the old high road 

 for this and other mammals from Asia into North America in 

 Pleistocene times. 



Linnean Society, November 2. — Prof. Stewart, President, 

 in the chair. — -The secretary having read a list of the donations 

 to the library since the last meeting, the President moved that 

 the thanks of the society be given to the donois and to Lady 

 Arthur Russell for the valuable collection of engraved portraits 

 of naturalists which she has been so good as to present to the 

 society in the name of her husband, the late Lord Arthur 

 Russell, a motion which was passed unanimously. The Presi- 

 dent then referred to the improvement which had been carried 

 out during the recess in the society's apartments by the intro- 

 duction of the electric light, for which they were indebted to the 

 liberality of the treasurer, Mr. Crisp, who on former occasions 

 had shown himself so generous a benefactor, and moved that 

 the hearty thanks of the society be given to Mr. Crisp for his 

 munificent present. The resolution was carried by acclamation. 

 Referring to the deaths of Fellows of the society which had oc- 

 curred since the last meeting, the President alluded especially to 

 the Rev. Leonard Blomefield, whose connection with the society, 

 extending over seventy years, had recently been maWe the subject 



NO. 1256, VOL. 49] 



