NATURE 



[April i, ig-.g 



coil ; A. E. Snow. In this method the coil Ihe self- 

 inductance L of which is to be measured is joined in series 

 with a condenser of capacity C, and the combination 

 forms one arm of a Wheatstone's bridge. The condenser 

 is shunted by a non-inductive resistance r. The result 

 L = Cr^, whence the value found for L is independent of 

 the inductance of the galvanometer, has been proved for 

 the case in which the discharge of the condenser is con- 

 tinuous. In this paper the case in which the discharge 

 of the condenser is oscillatory is dealt with, the applied 

 E.M.F. being constant. It is shown that the discharge 

 of the condenser is of the same nature as that through 

 the galvanometer. In the case of an oscillatory discharge 

 of the condenser the value found for the inductance of the 

 coil is not affected by the inductance of the galvanometer. 

 If the same method is applied to the case of an alternating 

 E.M.F., a result is obtained which involves the inductance 

 of the telephone used to indicate the current. From 

 general considerations this can be shown to be impossible. 

 The method used in the case of a constant E.M.F., there- 

 fore, is not available for the investigation of the case in 

 which the E.M.F. is alternating. — Exhibition of a high- 

 potential primary battery : W. S. Tucker. The object of 

 the battery is to maintain at known potentials such con- 

 ductors as the needle of the quadrant electrometer, for 

 charging condensers in capacity and insulation tests, and 

 so on. It is composed of a large number of elements in 

 scries, the elements consisting of carbon and pure zinc 

 with a nearly saturated solution of calcium chloride as 

 electrolyte. It is found possible to obtain 102 volts per 

 element, so that a total of more than 900 volts is given. 

 Since the terminals are well insulated, a very steadv voltage 

 is obtained, and this has been kept within one-tenth per 

 cent, variation for two hours and i per cent, for half a 

 day, the temperature of the room remaining steadv. The 

 battery has fitted to it an arrangement whereby any 

 desired voltage from that of one to that of all the cells 

 can be obtained by steps of one cell. \ snecial feature of 

 the battery is its careful insulation. — The least moment of 

 inertia of an angle-bar section : H. S. Rowell. 



Linnean Society, March 18.— Dr. D. H. Scott, F.R.S., 

 president, in the chair. — The " dry-rot " of potatoes : Miss 

 Sibyl Longman. The author pointed out, as the result 

 of her researches, that the disease of the potato tuber, 

 known as " dry-rot " — due to the fungus Fusaritim Solani 

 — is not necessarily preceded by " wet-rot," but may be 

 set up in sound tubers by inoculation with spores or 

 mycelium of Fusarium Solani, which species is not a 

 parasite of the resting tuber only; it may also attack and 

 kill the shoots of potato plants. The fungus, which prob- 

 ably exists as a widely distributed saprophyte in the soil, 

 infects the growing potato plant vid the' root ; it also 

 spreads from tuber to tuber during storage, and diseased 

 tubers may produce diseased plants. Heat sterilisation of 

 the^ resting potato tuber, with respect to Fusarium Solani, 

 is impracticable, for the death-temperature of the fungus 

 is higher than that of the potato. A pycnidial stage occurs 

 in the life-history of Fusarium Solani, which should there- 

 fore be placed in the highest group of the Fungi Imperfecti, 

 the Sphseropsidacese, and not, as is the case at present, in 

 the Hyphomycetes. — The structure and affinities of Davidia 

 involucrata, Baill. : A. S. Home. The paper deals with 

 the structure and affinities of a genus referred to the 

 natural orders Combretaceae, CornaceEe, and Hamame- 

 lidace.-E by various authorities, in the light of original 

 observations carried out under the direction of Prof. J. B. 

 Farmer, upon material brought by Mr. E. H. Wilson 

 from Szechuen in 1904. Evidence is advanced in favour of 

 interpreting the inflorescence as consisting of a number of 

 congenitally fused, apetalous, multi-stamiiiate male flowers, 

 or of male and in addition a single obliquely situated, 

 apetalous, hermaphrodite flower with epigynous stamens 

 arranged in series. From a detailed study of the flower, 

 ovary, ovule, and seed, the author is inclined to believe 

 tlu.t Oavidia is distantly related to Alangium and Nyssa, 

 and still more distantly related to the Araliaceje ; that the 

 genus occupies a somewhat isolated position owing to 

 having pursued an independent cour.se of development from 

 the plexus of primitive groups, which included the ancestral 

 forms of the .Xraliaccae, Nysseae, and AlangieEE. 



Edixel'rgh. 



Royal Society, March i. — Dr. R. II. Traquair, 

 F.R.S., vice-president, in the chair. — The systematic 

 motion of the stars, second paper : Prof. Dyson, Follow- 

 ing up a previous paper on the subject, the author, by 

 application of a statistical method, found that the two 

 streams were moving with velocities which were in the 

 ratio of 2 to 3. The stars belonging to the two streams 

 did not appear to have any other distinguishing character- 

 istics. — Preliminary note on Cynomacrurus Piriei, a new 

 deep-sea fish discovered by the Scottish National Antarctic 

 Expedition : Prof. Dollo. This new fish, named after Dr. 

 Pirie, surgeon and geologist to the Scotia, belonged to the 

 Macruridse, a family closely allied to the cod. The exist- 

 ence of Macrurida; within the Arctic Circle had been known 

 since 1837, when Sven Lov^n recorded Macrurus burglax 

 from Hammerfest, Finmark. In iSq') Prof. Dollo recorded 

 the first macrurid from the Antarctic, namely, the new 

 species Nematoneurns lecontii, brought home by the 

 Belgica. The new species now described differs generically 

 from these. It was obtained in lat. 71° 50' S., long. 23° 30' 

 W., at a depth of 2102 fathoms. 



March 15. — Dr. Traquair, F.R.S., vice-president, in the 

 chair. — The glacial deposits of western Carnarvonshire : 

 Dr. T. J. Jehu. The Lleyn promontory lay outside the 

 paths followed bv the native glaciers. Hence, instead of 

 the lowest Boulder Clay of the district east of Snowdonia, 

 there is a " rock rubble " or " head " which underlies 

 all the drift deposits, and is the result of subaerial waste 

 under severe climatic conditions. It is succeeded by (i) a 

 Lower Boulder Clay with northern erratics and shells ; 

 (2) sands and gravels ; (3) an Upper Boulder Clay with 

 northern erratics and shells. The Lower Boulder Clay, 

 which is the most widely spread of all these deposits, is 

 the product of a mer-de-glace coming from the north, which 

 overwhelmed Lleyn as far cast as a line running from 

 Carnarvon to Cardigan Bay, in the neighbourhood of 

 Pwllheli. The sands and gravels were accumulated during 

 a retreat of the ice, while the Upper Boulder Clay marks 

 a re-advance. So far as Lleyn is concerned, the two 

 Boulder Clays might be regarded as the product of one 

 nier-de-glace which was subject to considerable oscilla- 

 tions, but a review of the Irish Sea basin as a whole 

 renders it more probable that they are the products of the 

 ice-sheets of two Glacial epochs separated by an inter- 

 Glacial epoch. — The Glenboig fireclay : its halloysite and 

 sideroplesite : Prof. J. W. Gregory. Evidence was 

 adduced to show that this fireclay was laid down in a 

 wide lagoon in the beginning of the Millstone Grit period. 

 It contains lenticular crystals of sideroplesite, which have 

 been built up by zonal deposition around rhombohedra, 

 which probably crystallised in the water of the lagoon. 

 The clay substance which forms the base of the fireclay 

 is isotropic, and is referred to the mineral h.alIoysite. The 

 clay contains no kaolinite. — Tuesite, a Scottish variety 

 of halloysite : Prof. Gregory. Tuesite was founded as a 

 mineral species by Thompson in 183(1 for material described 

 as occurring in beds in the New Red Sandstone on the 

 banks of the Tweed, and has been identified with kaolinite. 

 The absence of china clay from Scotland has been used 

 as a strong argument in favour of the pneumatolitic origin 

 of that material, and the reported nature and occurrence 

 of tuesite would have been inconsistent with that origin. 

 Re-examination of the material shows, however, that the 

 tuesite occurs as an alteration product in a volcanic neck; 

 it is not kaolinite. but halloysite, and its formation is con- 

 sistent with the deep-seated origin of the great china-clay 

 masses found in manv parts of the world. 



Paris. 

 Academy of Sciences, March 15. — M. Beiichard in the 

 chair. — Systems of homogeneous differential equations : 

 Gaston Da.rboux. — The flow of rivers : Bouquet de la 

 Grye. It is generally assumed in works on hydraulics 

 that in water in motion under the action of gravity the 

 elementary strips move in a straight line, the flow being 

 expressed as a time function of the fall. This does not 

 -correspond with practice; the motion is in curved lines. 

 By applying the principle of least action, it is found that 

 the strips of liquid would have a tendency to turn to the 



NO. 2057, VOL. 80] 



