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NA TURK 



\_April 15, 1886 



quantities o, I, and m. Taking z, i, and n to be o, 6, and i 

 respectively, he showed that 2 + 2 = 3, 2x2 = 3^.— Mr. Tuckci 

 read a theorem in conies, by the Rev. T. C. Simmons. Through 

 the focus A' of an ellipse chords LKL', MK'.W' are drawn at 

 angles of 60° wilh the major axis. A new ellipse is described 

 having /i for focus, and LM', ML' for tangents at vertices. 

 Then it will follow that (i) the new ellipse will have the same 

 directrix as the former ; (2) its eccentricity will equal half that 

 of former; (3) an infinite number of triangles inscribed in the 

 outer, may be circumscribed about the latter ; (4) if the outer 

 ellipse be projected orthogonally into a circle, these projected 

 triangles will all have K for symmedian point, the inner ellipse 

 for Brocard ellipse, and the projections of the intersections of 

 LV, MM', with the inner minor axis for Brocard points ; (5) 

 the sine of the Brocard angle will be the ratio of the minor axes 

 of the ellipses, the ratio of the Brocard diameter to the 

 circum-radius will be the ectentricity of the outer ellipse, &c. 



Geological Society, March 24. — Prof. J. W. Judd, F.R.S., 

 President, in the chair. — Henry Fisher, Edwin Harman, Henry 

 Johnson, and Edward Alloway Parkhurst were proposed as 

 Fellows of the Society. — The following communications were 

 read : — On the genus DipJiyphylluin, Lonsdale, by James 

 Thomson, F.G.S. — On additional evidence of the occurrence of 

 glacial conditions in the Palceozoic era, and on the geological 

 age of the beds containing plants of Mesozoic type in India and 

 Australia, by Dr. W. T. Blanford, F.K.S., Sec G.S. After 

 recapitulating briefly the principal facts known as to the corre- 

 lation of the Karoo formation of South Africa, the Gondwana 

 system of India, and the coal-measures and associated beds of 

 Eastern Australia, and especially noticing those phenomena in 

 the different strata that had been attributed to the action of ice, 

 the author proceeded to describe the additions recently made to 

 previous knowledge by various members, past or present, of the 

 Geological Survey of India, and especially by Mr. R. Oldham 

 and Dr. Waagen. These additions had recently been published 

 in the Records of the Geological Survey of India. Mr. K. 

 Oldham, in a recent visit to Australia, had come to the same 

 conclusion as all other geologists 'who had visited the country, 

 and clearly showed, as the Rev. W, B. Clarke and many others 

 had done, that beds containing Glossopteris, PJiyllotheca, and 

 Nccggcrathiopsis were intercalated among marine beds with 

 Carboniferous fossils. The age of these marine beds was shown 

 by Dr. Waagen to be that of the European coal-measures. Mr. 

 Oldham had, however, further ascertained the presence in 

 abundance of smoothed and striated boulders, evidently trans- 

 ported by ice, in the marine Carboniferous beds north of 

 Newcastle, N. S. W., and he consequently considered these beds, 

 and not the overlying Hawkesbury, the equivalents of the 

 Bacchus-mar^h beds of Victoria, and of the Talchirs of India, a 

 view which was in accordance with the relations of the fossil 

 flora. Meantime Dr. Waagen had received from Dr. H. Warth 

 some fossils from the Salt-range of the Punjab. The fossils came 

 from the upper part of a boulder-bed, the resemblance of which 

 to the Talchir group at the base of the Gondwana system had 

 long been recognised, but which had hitherto been classed with 

 a stage immediately overlying, containing Upper Cretaceous 

 fossils. The fossils now found by Dr. Warth included two 

 forms of Coiiidaria found in the Australian Carboniferous rocks, 

 besides some other species evidently of Carboniferous age. Dr. 

 Waagen consequently classed the boulder-bed together with 

 other similar formations in other parts of the Salt-range as 

 Carboniferous. There was one difficulty, the fossils just re- 

 ferred to were considered by Mr. Wynne to be contained iu 

 pebbles derivative from another bed. It was, however, shown 

 that this did not affect the age of other boulder-beds in the Salt- 

 range, and that the latter were connected with the Talchir beds 

 in Central India by another discovery of Mr. R. Oldham's, that 

 a boulder-bed in the Indian deserts was also probably of Talchir 

 age, and that the question as to whether the nodules containing 

 the Conulariir, Sec, were concretions or pebbles might await 

 further examination in the field. Another contriliution to the 

 question had been made by Mr. Griesbach, who had recently 

 found a boulder-bed which, from its character and fossils, he 

 considered as Talchir, in the neighbourhood of Herat. It was 

 pointed out that the existence, over such extensive areas, of 

 boulder-beds, all of which might, without any improbability, be 

 of approximately the same age, rendered it highly probable that 

 all were really contemporaneous and due to one Glacial period ; 

 that this period must have been towards the close of the 

 Palaeozoic era, which it may possibly have terminated by exter- 



minating many of the principal forms of life. The peculiar 

 flora of the Australian Newcastle beds and of the Indian 

 Damudas, having nothing in common with the contemporaneous 

 European Carboniferous flora, afforded an important proof of 

 distinct botanical provinces in past times. 



Geologists' Association, April 2. — On grasses, by J. 

 StarMe Gardner, F.L.S. The paper was an inquiry as to the 

 geological period at which grasses first commenced to assume a 

 preponderating position in vegetation. Their value and im- 

 portance at the present day was first sketched, and it was re- 

 marlced that they occupy under cultivation one- third of the 

 entire area of Europe, inclusive of lakes and mountains, while, 

 exclusive of malt and spirituous drinks distilled fi-om them, 

 their products to the value of nearly one hundred millions 

 sterling are imported annually into this country alone. There 

 are over 3000 species, fitted to occupy most diverse stations and 

 to overcome nearly every kind of competition under no matter 

 what conditions, with the result that about 95 per cent, of the 

 plants growing in ordinal^ meadow-land are grasses. The 

 conclusion arrived at was that there was no great development 

 of grasses until towards the close of the Eocene, no definite 

 remains being associated with any of the older Eocene floras of 

 temperate latitudes. A number of facts were brought forward 

 to show that grasses could by no possibility have failed to 

 become associated with the remains of other plants in beds de- 

 posited under such conditions as those of the Eocene had they 

 existed in any profusion then, while further to sup]3ort this 

 argument it was stated that the very similar Oligocene and 

 Miocene beds all over Europe are crowded wilh them. Further 

 it was shown that the dentition of all the early Eocene herbi- 

 vorous Mammalia was adapted for crunching fruits, snapping 

 twigs, and grubbing up roots, rather than for browsing on such 

 food as grass, so that the evolution of true Graminivora, as 

 well as the specialised Carnivora that prey on them, must be 

 post-dated to the appearance of the grass itself. The geological 

 history of the whole class of insects was reviewed, with the 

 object of supporting the conclusion arrived at as to the post 

 mid-Eocene date of grass. Older remains of grass may, how- 

 ever, occur in the vast series of Tertiary deposits in Spitz- 

 bergen, but as yet their age has not been accurately correlated. 

 Finally, it was shown that the introduction of an aggressive 

 type in vast numbers and of different habits to pre-existing 

 vegetation, exerted an influence on terrestrial life altogether 

 without parallel, and for the first time rendered possible the 

 development of a meadow and prairie vegetation, as distinct 

 from that of marsh, scrub, and forest, with all the attendant 

 forms of animal and vegetable life to which such vegetation is 

 indispensable. 



Physical Society, March 27. — Prof. W. G. Adams, Vice- 

 President, in the chair. — Mr. A. R. Wright was elected a 

 Member of the Society. — The Chairman read a letter from Dr. 

 Alder Wright, Secretary to the "Tribe Fund" Committee, in 

 which reference was made to the scientific work of the late Mr. 

 Alfred Tribe, and an appeal made for funds to aid in the main- 

 tenance and education of his family, which, owing to his early 

 death, has been left in sti-aitened circumstances. — The follow- 

 ing communications were read : — On an arc lamp convenient for 

 use with the Duboscq lantern, by Prof S. P. Thompson. The 

 old Duboscq lamp, though working well with a series of Grove's 

 cells, is very unsuitable for use with currents from dynamos. 

 Prof Thompson has employed as a substitute in the Duboscq 

 lantern a lamp commonly known as the " Belfast arc lamp." 

 The result is all that can be desired as regards steadiness and 

 regularity. The focusing, that is, the adjustment of the arc so 

 that it shall remain unchanged in position, is effected by a 

 wheel below the lantern, which is moved by hand.— On a modi- 

 fied Maxwell's galvanometer, by Prof. S. P. Thompson. The 

 galvanometer consists of a light frame of copper, upon which is 

 a coil of wire. This is suspended between the poles of a horse- 

 shoe magnet, and a piece of soft iron is placed within the coil, 

 but free from it, which concentrates the magnetic force between 

 the poles. The coil is suspended by two silver wires, by which 

 it is in connection with two binding screws on the base of the 

 instrument. The galvanometer is extremely simple in adjust- 

 ment, and very dead beat ; it has also the advantage of being 

 affected to an inappreciable extent by neighbouring magnets aiid 

 currents, with a current in its own coils ; when no current is in it, 

 it is of course quite unaftected. The reading is effected liy the 

 ordinai7 lamp, mirror, and scale arrangement. — On the expansion 



