March 27, 1902] 



NA TUBE 



503 



years 1S99-1901. — The Astronomer Royal presented a paper on 

 new variable stars found at the Royal Observatory during the 

 measurement of plates for the Astrographic Catalogue, and also 

 a series of measures of double stars made at Greenwich with the 

 28-inch refractor. Prof. Turner described an instrument for 

 rapidly comparing two star plates of the same region, and Mr. 

 Lewis spol<e upon the orbit of 5 Equulei.— Mr. Maunder gave 

 an account of a paper from the Royal Observatory on the mean 

 areas, i:c., of sun-spots in the year 1901, and referred to the 

 apparent connection between the large sun-spot of May 1901 

 and the disturbed portion of the corona as shown on the eclipse 

 photographs. — Mr. Dyson gave a summary of a paper from the 

 Royal Observatory on the parallax and proper motion of Nova 

 Persei. — Mr. H. C. Plummer partly read a paper on the images 

 formed by a parabolic mirror. — Mr. Whittaker read a paper on 

 periodic orbits in the restricted problem of three bodies, being 

 an extension of the paper read at the January meeting. The 

 problem considered was that of tinding the motion of a small 

 planet under the attraction of the sun and a large planet, the 

 latter being supposed to move in a purely circular orbit. Two 

 theorems were communicated in the paper, the first giving a 

 criterion for the existence of periodic orbits and the second 

 being concerned with the value of an integral taken over the 

 orbit. — A note by Mr. Fourcade was read, on Prof. Turner's 

 recent paper on photographic surveying. 



Mathematical Society, March 13. — Major P. A. 

 MacMahon, F.R.S., vice-president, and subsequently Lieut. -Col. 

 A. Cunningham, R.E. , in the chair. — The Rev. J. CuUen read 

 a paper on the solutions of a system of linear congruences. The 

 object of the paper is to give a graphical process for obtaining 

 the solutions of a system of linear congruences under a given 

 limit ; and the scope of the paper consists in establishing and 

 explaining four simple rules to be employed in applications of 

 the process ; the process yields new results in the resolution of 

 high numbers, having factors of unknown form, into sums of 

 squares. — Mr. G. H. Hardy communicated a paper on the theory 

 of Cauchy's principal values. This paper is the third of a series 

 concerned with the interpretation, and the use in analysis, of 

 such divergent definite integrals as have in Cauchy's sense a 

 principal value ; it deals in particular with the possibility of 

 differentiation and integration under the sign of the principal 

 value, and gives sufficient criteria for the validity of the inter- 

 change of order of the limiting operations involved ; the theory 

 is illustrated by numerous examples of the calculation of definite 

 integrals by processes which had not previously been proved to 

 be valid. — Mr. R. Hargreaves read a paper on algebraic relations 

 between ional harmonics of different orders. The coefficients 

 in any sequence equation connecting zonal harmonics are 

 rational functions of the orders of the harmonics, and these 

 functions also are connected by sequence equations ; the latter 

 equations are developed systematically. — Dr. F. S. Macaulay 

 made a preliminary communication of some results in the theory 

 of elimination. He showed how to express the resultant of any 

 number of homogeneous equations in any number of variables as 

 a quotient of two determinants. — The following paper was 

 communicated from the chair: Mr. J. Buchanan, on quadrature 

 formulae. The formulas are obtained by the use of methods of 

 interpolation based upon central differences. 



Entomological Society, March 5. — The Rev. Canon 

 Fowler, president, in the chair. — Mr. L. B. Prout exhibited, 

 on behalf of Mr. J. P. Mutch, Vanessa {Eiigonia) poiychloros, 

 L., a 9 bred by Mr. H. Baker from pupa from Stowmarket, 

 Suffolk, the ground-colour much darkened and the black 

 markings somewhat enlarged; Ckrysophamis phlaeas, L. , an 

 aberration (captured in the Isle of Wight, August, 1901) much 

 suffused with dark colour, especially at outer margin and on 

 hindwings, only a very small patch of the red colour remaining 

 at the inner angle of the latter ; Agrotis pitta^ Hb. , a perfectly 

 halved gynandromorphous example, and NoUiia sobrina, Gn., 

 an aberrant specimen with white antenna; and a somewhat 

 hoary appearance on the forewings, taken in East Aberdeen- 

 shire, August, 1900. — Mr. A. Bacot exhibited a series of vl/a/a- 

 cosoina castrensis and a series of M. neustria for comparison 

 with a hybrid brood, resulting from a pairing between a male 

 neustria and a female castrensis. This was the first time any 

 exhibition of experiments of the kind had been made before 

 the Society by British investigators, though Mr. Merrifield had 

 shown a number of crosses bred by Herr Standfuss. The 

 sexes, as exhibited, were very clearly distinguishable, and 

 there was not much tendency to gynandromorphism, though 



NO. 1 69 I, VOL. 65] 



of sixty or seventy specimens almost every 9 showed some 

 signs of S coloration.— Mr. O. E. Tansan exhibited a pair of 

 Stephanocratcs dohertyi, Jord., a Goliath beetle discovered by 

 the late W. Doherty in the highlands of British East Africa.— 

 Dr. T. A. Chapman exhibited cocoons of a Limacodid moth 

 from La Plata, with empty oupa-cases of a dipterous parasite 

 of the genus Systropus. The resemblance between the two 

 pupa - cases is, however, not merely of appearance, but 

 functional also. The moth-pupa, i.e. the moth itself inside the 

 pupa-case, almost certainly by inflating itself with air, to 

 secure greater size and a stiffened epiderm as a basis of mus- 

 cular action, exerts an end-to-end pressure within the cocoon, 

 and so forces off a lid. The Systropus breaks off a similar 

 lid, no doubt by similar end-to-end pressure to that exerted by 

 the moth, Diptera having highly developed the habit of in- 

 flating themselves with air, at emergence from the pupa. This 

 pupa also has a beak very like that of the Limacodid, but even 

 stronger and sharper.— Mr. J. E. Collin, in further illustration 

 of Dr. Chapman's remarks, exhibited specimen? of Systro- 

 pus, sp. ? from Buenos Ayres, parasitic on a Bombycid Lepi- 

 dopteron {Liniacodes ?). This, he said, was possibly the same 

 as Dr. Chapman would have reared from his cocoons. The 

 species was apparently undescribed, but most allied to S. brasil- 

 ieiisis, Meg. — Prof. E.B. Poulton, F.R.S., readapaper entitled 

 " Five years' observations and experiments (1897-1901) on the 

 bionomics of South African insects, chiefly directed to the 

 investigation of mimicry and warning colours," by Guy A. K. 

 Marshall, with appendices containing descriptions of new 

 species, by W. L. Distant and Colonel C. T. Bingham.— Mr. 

 Malcolm Burr contributed a monograph of the genus Acrida 

 with notes of some allied genera and descriptions of new species 

 — Dr. D. Sharp, F. R.S., contributed three papers by Mr. 

 R. C. L. Perkins, respectively entitled : (a) Notes on 

 Hawaiian wasps, with descriptions of new species"; (/;) "Four 

 new species and a new genus of parasitic Hymenoptera (Ich- 

 neumonidne) from the Hawaiian Islands"; and (t) "On the 

 generic characters of Hawaiian Crabronida; : four new genera 

 characterised." 



Geological Society, March" 12. — Sir Archibild Geikie, 

 F. R. S. , vice-president, in the chiir. — The crystalline limestones 

 of Ceylon, by Mr. Ananda K. C^omara-Swamy. The crystal- 

 line rocks of Ceylon may be divided into three series : (i) The 

 older gneisses; {2) the crystalline limestones; (3) the granu- 

 lites (charnockite series) — pyroxene-granulite, leptynite, &c. 

 A local subdivision of this series is the Point de Gille group — 

 wollastonite-scapolite-gneisies, &c. The crystaUine limestones 

 of Ceylon are intimately a isociated with the banded pyroxene- 

 and acid granulites (charnockite series). They form bands 

 with outcrops from a few feet to more than a quarter of a mile in 

 width, interbedded with the granulites. The limestones fhem- 

 selves have a banded structure (foliation) parallel to that of the 

 granulites and to the boundaries. Although the relation of the 

 granulites to the limestones is on the whole intrusive, the two 

 rocks in their present condition are essentially contemporaneous, 

 and seem alike to have consolidated from a molten magma. 

 The calcite occurring in the granulites near the contact has all 

 the appearance of an original mineral. The foliation of the lime- 

 stones is regarded as a sort of flow-structure, and corresponds 

 with that of the granulites to which it is always parallel. That 

 the foliation does not result from the action of earth-movements 

 on a solid rock is shown by this, that the very minerals whose 

 variable distribution is one of its chief causes have certainly 

 not been affected by deforming earth-movements, nor are they 

 such as to have been produced by these ; moreover, in this 

 respect a distinction cannot be made between the limestones and 

 granulites, which would necessarily have suffered alike had they 

 been subjected to deforming strains since the consolidation of 

 the latter. The original nature of the limestones is less evident ; 

 they may have been sedimentary or tufaceous, and, if so, sub- 

 sequently softened and metamorphosed ; or possibly ah initio 

 truly igneous rocks, and related to the charnockite-magma. 

 Reasons for and against these views are given. The relations 

 between the crystalline limestones and nepheline-syenites of 

 AIno have suggested to Prof. Hogbom that perhap; the lime- 

 stone may have been a product of the nepheline-syenite magma 

 there. The author feels sure that the crystalline limestones of 

 Ceylon have not arisen by the alteration of the basic lime- 

 silicates of the pyroxene-granulites. — On Proterozoic gastero- 

 poda which have been referred to Murchisonia and Pleuroto- 

 maria, with descriptions of new subgenera and species, by Miss 



