24 



NATURE 



{Nov. 7, 1889 



■whose directions are parallel to the principal planes of the two 

 Nicols. The crystal under examination is then placad with one 

 edge under one of the cross-wires ; if the field of vision remains 

 •dark, then the planes of vibration in the crystal are known to 

 cirrespond to the chief planes of the two Nicols. If, however, 

 the field of vision becomes bright the crystal must be rotated, by 

 means of a graduated, object-carrier until it is again dark. The 

 angle through which the carrier has been rotated is a measure of 

 the angular inclination of the planes of vibration to the edges of 

 the crystal. When convergent polarized light is used, the majority 

 •of crystals of organic substances, which are mostly biaxial, 

 exhibit a lemniscate whose poles are at varying distances apart 

 for various crystals. The distance between the poles of the 

 lemniscate may be measured by suitable methods, is extremely 

 ■characteristic for those crystals of greatest physiological im- 

 portance, and may be used, in conjunction with the measurement 

 ■of the planes of vibration, as a very certain means of determining 

 the crystal. The pleochromatism of n^any crystals is itself in 

 many cases sufficiently characteristic. — Dr. Virchow described 

 the distribution of blood-vessels in the eye of Selachians, and 

 the several types according to which the vessels are developed in 

 the eyes of various classes of animals. — Dr. Benda made a com- 

 munication to the effect that the coiled glands which are so widely 

 distributed as sweat-glands in the skin when they exhibit an 

 enlarged secretory part, and a more complicated structure, are 

 known as cerumenous and as mammary glands. They are 

 •characterized specially by the fact that during secretion there is 

 no destruction of their epithelium. These modifications of the 

 typical coiled glands have been found by Dr. Benda in large 

 numbers and widely spread in the skin of Protopterus. — Dr. 

 Schneider spoke on the distribution and significance of iron in 

 the animal organism. He was able to find iron in greater or less 

 quantity in the cell protoplasm and nucleus of all classes of 

 animals, the liver and spleen being the organs in which its 

 occurrence was most marked. The connective tissues were very 

 rich in iron, and it was found with similar constancy in the cuticular 

 layers and quite constantly in the extreme tips of fishes' teeth. 

 The more he extended his investigations over the most widely 

 differing classes of animals, whether on land, or in fresh-water, or 

 in the sea, and the more widely different were the organs he 

 examined, by so much the more was it seen that iron is universally 

 present in the animal organism. Its importance is preeminently 

 physiological. 



Amsterdam. 

 Roy 1 Academy of Sciences, September 28. — Prof, van 

 ■der Staals in the chair. — M, Suringar dealt with the Melocacti 

 •of Aruba, stating what he had himself observed concerning the de- 

 velopment of those plants from seed and their subsequent growth. 

 He spoke also of the manner in which the Melocacti might be 

 classified according to their natural affinities, and sketched a 

 pedigree of the species. — M. Schoute spoke of tetrahedra, 

 bounded by similar triangles, and described a new species with 

 pairs of opposite edges i and r^, r and r, r"^ and r-. 



Stockholm. 

 Royal Academy of Sciences, Octob3r 9. — Musci Asize 

 Borealis (second part) : feather mosses, by the late Prof. S. O. 

 Lindberg, of Helsingfors, and Dr. H. W. Arnell.— On the per- 

 manent committee for a photographic map of the heavens and 

 its work, by one of its members, Prof. Duner.— On the Metre 

 Congress in Paris, September 14-28, this year, and on the 

 prototypes of the metre and the kilogramme, by Prof. Thalen.— 

 Emanuel Swedenborg as a mathematician, by Dr. G. Enestrom. 

 —On naphtoe acids, by Dr. A. G. Ekstrand.— Chemical investi- 

 gation of some minerals from the neighbourhood of Langesund, 

 by Herr H. Biickstrom. — An attempt to determine the velocity 

 of light from observations on variable stars, by Dr. C. Charlier. 



DIARY OF SOCIETIES. 

 London. 



THURSDAY, November 7. 



LiNMBAN Society, at 8.— On a Collection of Dried Plants chiefly from the 

 bouthern Shan States, Upper Burma : Colonel H. CoUett and W Bottin'^ 

 Hemsley, F.R.S. ° 



Chemical Societv, at 8.— The Isolation of a New Hydrate of Sulphuric 

 Acid existing in Solution : S. U. Pickering.— Further Observations on the 

 Magnetic Rotation of Nitric Acid, of Hydrogen Chloride, Bromide and 

 Iodide in Solution: Dr. W. H. Perkin, F.R S.— On Phosphoryl Tri- 

 fluoride : T. E. Thorpe, F.R.S., and F. T. Hambly.— On the Acetyla- 

 tion of Cellulose : C. F. Cross and E. Bevan.— On the Action of Light on 

 Moist Oxygen: A. Richardson.— Anhydracetophenonebenzil and the 

 Constitution of Linius lepideus : Drs. Japp, F.R.S., and Klingsman. 



FRIDAY, November 8. 

 Royal Astronomical Society, at 8. 



MONDAY, Nove.'viber ii. 

 Royal Geographical Society, at 8.30.— Cyprus : Lieut. -General Sir 

 Robert Biddulph, GC.M.G. 



TUESDAY, November 12. 

 AvTHROPOLOGiCAL INSTITUTE, at 8.30. — Observations on the Natiira 



Colour of the Skin in certain Oriental Races: Dr. J. BedJoe, F.R.S.— 



Manners, Customs, Superstitions, and Religions of South African Tribes : 



Rev. James Macdonald. 

 Institution of Civil Engineers, at 8.— Inaugural Address of Sir John 



Coode,_ K.C.M.G., President, and Presentation of Medals, Premiums, 



and Prizes awarded during Last Session. 



WEDNESDAY, November 13. 

 Royal Microscopical Society, at 8. 



THURSDAY, November 14. 

 Mathematical Society, at 8.— Isoscelian Hexagrams : R. Tucker.— On 

 Euler's ^-Function : H. F. Baker. 



FRIDAY, November is. 



Physical Society, at 5.- On the Electrification due to the Contact of 

 Gases and Liquids : J. Enright.— On the Effect of Repeated Heating and 

 Cooling on the Eiectrical Resistance and Temperature Coefficient of 

 Annealed Iron : H. Tomlinson, F.R.S. — Notes on Geometrical Optics, 

 Part II.: Prof. S. P. Thompson. 



IvsriTUTiON of Civil Engineers, at 7.30.— The New Harbour and 

 Breakwater at Boulogne-sur-Mer : S. C. Bailey. 



BOOKS, PAMPHLETS, and SERIALS RECEIVED. 



A Popular Treatise on the Winds : W. Ferrel (Macmillan).— South African 

 Butterflies; vol. iii., Papilionidje and Hesperidas : R. Trimen and J. H. 

 Bowker (Trubner).— Light. 2nd edition : P. G. Tait (Edinburgh, Black).— 

 The Vertebrate Animals of Leicestershire and Rutland : M. Browne (Birm- 

 ingham, M. E. C.).— Sitzungsberichte der k. b Gesellschaft der Wis?en- 

 schaften Math.-Naturw. Classe, 1889, i. (Pra?).— Outlines of a Course of 

 Lectures on Human Physiology: E. A. Parkyn (Allman). -Flower- Land: 

 R. Fisher (Bemrose).— Potential and its Application to the Explanation of 

 Electrical Phenomena: R. Tumlirz. translated by D. Robertson (Riviiig- 

 tons).— Index Catalogue of the Library of the Surgeon-General's Office, 

 United States Army, vol. x. (Washington).- The Birds of Berwickshire, vol. 

 i. : G. Muirhead (Edinburgh, Douglas).— Idylls of the Field : F. A. Knight 

 (E. Stock). — Atti della Reale Accademia delle Scienze Fisiche e Matema- 

 tische, serie seconda. vol. iii. (Napoli). — Ferneries and Aquaria: G. Eggett 

 (Dean).— Traite Encyclopedique dePhotograph.e, 15 Octr. (Paris). 



CONTENTS. PAGE 



Twenty Years i 



Modern Views of Electricity 5 



The Calculus of Probabilities. By F. Y. E 6 



Argentine Ornithology. By R. Bowdler Sharpe ... 7 

 Our Book Shelf:— 



Benedikt and Knecht : "The Chemistry of the Coa!- 



Tar Colours." 8 



Gore: " A Bibliography of Geodesy " 9 



Letters to the Editor : — 



The Method of Quarter- Squares. — ^J. W. L. Glaisher, 



F.R.S 9 



Darwinism. — Prof. E. Ray Lankester, F.R.S. . . 9 



Record of British Earthquakes. — Charles Davison . 9 



Effects of Lightning.— W. G. S 10 



Electrical Cloud Phenomena. — Prof. W. K. Burton 10 

 The Use of the Word Antiparallel. ( With Diagrams.) 



— W. J. James 10 



Fossil Rhizocarps. — Sir J. Wm. Dawson, F.R.S. . 10 



Specific Inductive Capacity. — W. A. Rudge .... 10 

 Who discovered the Teeth in Ornithorhynchus ? — Dr. 



C. Hart Merriam . 11 



On the Hardening and Tempering of Steel, (illus- 

 trated.) By Prof. \A^. C. Roberts- Austen, F.R.S. . n 

 On a New Application of Photography to the Demon- 

 stration of Certain Physiological Processes in 



Plants 16 



Notes 17 



Our Astronomical Column : — 



Stellar Parallax by Means of Photography 19 



Measurements of Double Stars 19 



Barnard's Comet, 1888-89 20 



Biographical Note on J. C. Houzeau 20 



The Karlsruhe Observatory 20 



Objects for the Spectroscope 20 



Geographical Notes 20 



The Institution of Electrical Engineers 21 



University and Educational Intelligence 23 



Societies and Academies 23 



Diary of Societies . . 24 



Books, Pamphlets, and Serials Received 24 



