336 



NATURE 



\yan. 31, 1889 



relative to M. Vaschy's recent note on the propagation of the 

 current in a telegraph line, by M. L. Weiller. The author 

 questions on theoretical grounds some of M, Vaschy's con- 

 clusions, on which has been based an application for a patent. 

 M. Weiller submits a specimen of a telephonic cable with two 

 conductors constructed for the purpose of obtaining by self- 

 induction the compensation of the electro-static capacity. In 

 this apparatus the increase of the coefficient of self-induction is 

 obtained by inclosing the chief copper conductor in a covering 

 of soft iron wire.— Observations of the partial lunar eclipse of 

 January 16, 1889, made at the Obser^'atory of Lyons, by M. G. 

 Le Cadet ; and at the Paris Observatory, by MM. D. Eginitis and 

 Maturana. The observations at Lyons were made with the 

 Gautier equatorial coiidi, and at Paris with the west equatorial 

 in the garden. In the latter place the atmospheric conditions 

 were favourable at the commencement and towards the close of the 

 eclipse ; bat during the middle period the sky became overcast, 

 preventing the complete observation of all the phases. — Experi- 

 mental verification of M. Charles Soret's method for measuring 

 the indices of refraction in crystals with two axes, by M. Louis 

 Perrot. In a previous note {Comptes rendus, cvii. p. 176), M. 

 Soret showed that the three chief indices of refraction in a 

 crystal with double axis may be deduced from the limiting angles 

 of total reflection on any given faces. M. Perrot has now 

 verified this method by experiments with ordinary tartaric acid, 

 employing a Liebisch refractometer for the purpose. — On the 

 electric conductibility of salts in solution, by M. Lucien 

 Poincare. The author finds that the high polarization of a 

 silver electrode plunged into a saline solution, such as the nitrate 

 of potassa, falls immediately to zero by adding a trace of the 

 nitrate of silver. From this phenomenon follows a means of greatly 

 simplifying in certain cases the method hitherto employed by 

 MM. Bouty and Poincare for measuring the electric resistances 

 of saline solutions. — Papers were contributed by M. Ch. 

 Antoine, on the expansion and compression of atmospheric air ; 

 by MM. C, Vincent and Delachanal, on the extraction of sorbite ; 

 by M.J. Meunier, on the dibenzoic acetal of sorbite ; by M. A. 

 de Lapparent, on the relation of the acid eruptive rocks to the 

 phenomenon of the solfataras ; and by M. II. Morize, on the 

 Widmanstatten figures, illustrated by two photographs obtained 

 in direct and diffused light. 



Berlin. 

 Physical Society, December 28.— Prof. Kundt, President, 

 in the chair. — Dr. Ritter demonstrated, with the help of an 

 electric arc-lamp, the action of the ultra-violet rays on the 

 electrical discharge at the negative pole. — Dr. Lummer spoke 

 on photometers, and deduced, from the experiences gained with 

 the existing instruments, the following as requirements in their 

 construction : in the first place, the surfaces whose brightness of 

 illumination is to be equalized must not be separated by even 

 the narrowest intervening space ; and in the second, the outline 

 of the surfaces must be sharply defined. The first of the above 

 requirements is satisfied in Bunsen's grease-spot photometer, but 

 not the second, A further drawback arises from the fact that 

 the grease-spot reflects light, and the paper allows some to pass 

 through, so that both the spot and the surrounding surface are 

 always illuminated by both sources of light. An ideally perfect 

 photometer ought to reflect no light from its grease-spot, and be 

 impermeable to light over the rest of its surface. The speaker, 

 working in conjunction with Dr. Brodhun, had obtained the 

 above desiderata by purely optical means. When two total- 

 reflection prisms are placed with their hypotenuse surfaces in 

 juxtaposition, and two of the surfaces of the glass-cube thus 

 formed are illuminated by light from bright surfaces, then on 

 looking through the combination of prisms the only light which 

 reaches the eye will be that which enters laterally, whereas, that 

 which enters from the opposite side cannot reach the eye. 

 When a drop of Canada-balsam, whose refractive index is very 

 nearly the same as that of the glass, is placed between the 

 opposed hypotenuse surfaces, total reflection is done away 

 with at the place where the drop lies, and thus by illumina- 

 tion from one side only either a bright spot is seen on a dark 

 ground or a dark spot on a bright ground. When the 

 illumination is made from both sides, equality of illumination 

 can be easily established by adjusting the relative distances of 

 the sources of light until the spot disappears entirely. The drop 

 of Canada-balsam very soon loses its sharply-defined edges, 

 hence some other mode of procedure became necessary. The 

 central portion of the hypotenuse surface of one of the total- 



reflection prisms was left untouched, while the rest of the 

 surface was ground to a slightly spherical shape. When the 

 surfaces of the prisms were now firmly pressed together, light 

 passed without hindrance across the point of close contact of the 

 surfaces, whereas it was totally reflected at all other points. By 

 this means an ideally perfect "grease-spot " was obtained, which 

 was permeable to light, but reflected none, while the surround- 

 ing area reflected light completely and allowed none to pass 

 through. A third method for obtaining an ideally perfect 

 grease-spot consisted in etching figures on one of the reflecting 

 surfaces of the prisms ; the etched portions were perfectly 

 transparent, the rest of the surface reflected light completely. 

 The speaker exhibited photometers constructed according to the 

 above methods, and proved theoretically that the ideally perfect 

 grease-spot bears to the real one the ratio of i to 2, accord- 

 ing to the constants determined in the Imperial Physico- 

 Technical Institute. The sensitiveness of the new photometer 

 is about I per cent. 



BOOKS, PAMPHLETS, and SERIALS RECEIVED. 



Realistic Elementary Geography : W. G. Baker (Blackie). — Elementary 

 Inorganic Chemistry : A. H. Sexton (Blackie). — Insect Life, vol. i. No. 

 6 (Washington).— Mineral Statistics of Victoria, 1887.— Report of the Secre- 

 tary for Mines (Melbourne). — Les Levers Photographiques et la Photographic 

 en Voyage : Dr. G. Le Bon (Paris, Gauthier-Villais).-^Annuaire pour I'an 

 1889, par le Bureau des Longitudes (Paris, Gauthier-Villars). — A Te.xt-book 

 of Human Physiology, 4th ed. : Dr. A. Flint (Lewis).— Manuel Pratique de 

 Cristallographie : G. Wyrouboff (Paris, Gauthier-Villars). — An Illustrated 

 Manual of British Birds, Parts 8, 9, 10: H. Saunders (Gurney and Jackson). 

 — Annali di Agricultura, 1888 : Prof. Giglioli (Rome, Rotta). — The Assistant 

 to the Board of Trade Examinations: Captain Forbes (Relfe). — State 

 Museum of Natural History, Albany. N.Y.. 41st Annual Report (Troy). — 

 A Text-book of General Astronomy : Dr. C. A. Young (Ginn). — La Legge 

 del Diretto in Rispetto alle varie leggi di Natura : Prof. G, A. Longo 

 (Catania, Martinez). — New Commercial Plants and Drugs, No. 11: T. 

 Christy (Christy). — A Bibliography of Indian Geology: R. D. Oldham 

 (Calcutta). — Report of the Commissioners on Inland Fisheries and Game for 

 Year ending December 31, 1888 (Boston). — Journal of the Royal Statistical 

 Society, December (Stanford). — Archives Italiennes de Bioloeie, Tome xi. 

 Fs.sc. I (Turin, Loescher).— Himmel und Erde, Heft 5 (BerhD, Paetel).— 

 Beiblatter zu den Annalen der Physik und Chemie, 1888, No. 12 (Leipzig, 

 Barth). 



CONTENTS. PAGE 



Mind in Man and Brute. By Prof, C. Lloyd 



Morgan 313 



The Microscopical Study of Minerals in Rocks . 315 



Sewage Treatment, Purification, and Utilization . 316 

 Our Book Shelf:— 



" The International Annual of Anthony's Photographic 



Bulletin" 31? 



Abney: " Instiruction in Photography " 317 



Stewart: " Lessons in Elementary Physics " .... 317 

 Letters to the Editor:— 



Supposed Fossils from the Southern Highlands, — The 



Duke of Argyll, F.R.S 317 



Mr, Howorth on the Variation of Colour in Birds, — 



Prof. Alfred Newton, F.R.S 318 



Constitution of the Chlorides of Aluminium and the 

 Allied Metals.— Dr. B. Brauner ; Dr. Sydney 



Young 3*8 



Remarkable Rime and Mist.— E. J. Lowe, F.R.S. . 319 



Cercyonis alope and ncphele.—^9xn.Vi€\. H. Scudder . 319 

 Modern Views of Electricity. XIII. By Prof. Oliver 



J. Lodge, F.R.S 319 



A Jamaica Drift-Fruit. {Illustrated.) By D, Morris 322 



Haze. By Prof. J. H. Poynting, F,R,S 323 



The Earthquake at Edinburgh 324 



Decomposition of Nickel and Cobalt 325 



Notes 326 



Our Astronomical Column : — 



Rousdon Observatory, Lyme Regis 328 



Astronomical Phenomena for the Week 1889 



February 3-9 328 



Geographical Notes 32S 



The Present State of Seismology in Italy. By Dr. 



H, J. Johnston-Lavis 329 



Friendly Societies and their Funds 332 



Waterspouts in the Hughli. By S. R. Elson ... 333 



Scientific Serials 334 



Societies and Academies 334 



Books, Pamphlets, and Serials Received 336 



