576 



NATURE 



[April 12, 1888 



Trouvelot, this appearance may be explained by a bridge cross- 

 ing the spot, and sufficiently thin in some parts to escape 

 detection. — MM. Giovannozzi, at Florence, and Bruquiere, at 

 Marseilles, sent some observations on the zodiacal light, which 

 has been very bright ; M. Gourdet, observations on 66 Ceti ; 

 and M. Guiot on Mira Ceti and v Leporis. — M. Dumenil, at 

 Yebleron, observed a meteor on February 19 whose trace re- 

 mained visible for five or six minutes. — Observation of a fine 

 meteor at Paris on February 24 by M. Mabire at 7 p.m. — M. de 

 la Fresnaye submitted a plan of binocular telescope with total 

 reflecting prisms to bring the two oculars within convenient 

 distance for the two eyes. — M. Armelin, writing upon the 

 calendar reform, said that it was perhaps entering on a practical 

 phase. — The meeting thanked Mr. Holmes fjr his letter 

 published in the ^English Mechanic. His observation of the 

 comes to Polaris with a ij-inch is thought remarkable. — M. 

 Flammarion read a paper on a probable connection between 

 the movements of our sun and those of o Centauri. — General 

 Parmentier, reading a paper on the asteroids, remarked that the 

 new planets discovered do not fill up the gaps to which he 

 formerly called attention. — Various communications: on the 

 lunar eclipse of January 28, by M. Moussette ; a drawing of 

 Plato, by M, Schmoll ; observations on the aurora borealis, 

 by M. Trouvelot ; on a natural classification of double and 

 multiple stars, by M. Flammarion ; Vogel's chart of stellar 

 spectra, presented by M. Secretan. 



Berlin. 



Physical Society, March 16. — Prof, von Helmholtz, Pre' 

 sident, in the chair. — Doctor Koepsel demonstrated two energy 

 meters constructed on different principles by Messrs. Siemens 

 and Halske, and explained the arrangements of the same. — Prof. 

 Lampe spoke on a deficiency in elementary text -books of 

 mechanics — namely, that they do not employ the elliptic 

 functions so fully treated of by Gauss and Schellbach. The 

 speaker then showed by a series of examples how easy it is to 

 solve a number of mechanical problems by the use of these 

 functions. — Prof. Helmholtz next showed how the nature of 

 elliptic functions can be made clear to persons unacquainted 

 with them by means of the movement of a pendulum. — He then 

 briefly communicated the results of an investigation by Prof. 

 Topler, of Dresden, which he had yesterday laid before the 

 Academy of Sciences: it contains a new method for the measure- 

 ment of the magnetism and diamagnetism of gases. An index 

 drop of petroleum is placed in a glass tube bent at a very obtuse 

 angle ; on one side of the index is the gas which is to be investi- 

 gated and on the other side is atmospheric air. When placed 

 between the poles of a powerful electro-magnet, the index is 

 moved according as the gas is more or less strongly attracted than 

 the air : the amount of displacement is measured by a microscope. 

 The delicacy of the method is extremely great. It was in this 

 way observed that oxygen is most magnetic, then come air and 

 nitric oxide ; nitrogen, hydrogen, carbonic oxide, carbonic acid 

 gas, and nitrous oxide, on the other hand, are diamagnetic. 

 The method employed in the above research can also be applied 

 to the solution of various other problems, as, for instance, the 

 determination of the pressure of small columns of gases. 



Physiological Society, March 23. — Prof. Munk, President, 

 in the chair. — Dr. Benda spoke on the structure of ganglion- 

 cells, demonstrating at the same time, by means of specimens, 

 his method of hardening the brain and spinal cord, which con- 

 sists in treating them with nitric acid and potassium chromate. 

 His further communication dealt with certain differences, now 

 largely reconciled, in the results obtained by the speaker and by 

 Prof. Flesch, of Bern, who was present at the meeting. The 

 two observers now agree that certain ganglion-cells readily take 

 up colouring-matter, while others do not, and to these Prof. 

 Flesch attributes a difference in physiological function. Both 

 observers further admit the existence of dark granulations in the 

 protoplasm of the cells, but opinions differ as to the significance 

 of the same. — Dr. Claude du Bois Reymond stated that he had 

 long ago planned an investigation of the pupil when in darkness, 

 and that this intention had only become realizable since the intro- 

 duction of instantaneous photography by means of the momentary 

 illumination produced by magnesium. Miethe,the discoverer of the 

 method of momentary illumination with magnesium, has in this 

 way taken a photograph of his own pupil after it had been exposed 

 to complete darkness for forty minutes. As shown by the two 

 photographs which were exhibited the result was most surprising : 

 the diameter of the pupil was 9 to 10 mm., while the iris was at 



the same time reduced to a width of ij to 2 mm. — Prof. Gad 

 gave an account of experiments which had been made by 

 Sawyer, at his suggestion, with a view to determining whether the 

 separation of irritability and conducting power, which is so often 

 observed by neuropathologists, has any real physiological ex- 

 istence. When a part of the sciatic nerve, in accordance with 

 Griinhagen's method, was exposed for some time to the action of 

 a current of carbonic acid gas, it was found to be capable of con- 

 veying impulses generated by stimuli applied to parts of the 

 nerve more centrally situated, but was itself insensitive to 

 electrical stimulation applied directly to it, as Griinhagen had 

 already found. When that part of the nerve inclosed in the 

 chamber was exposed to the action of diluted vapour of alcohol, 

 the result was exactly the opposite, the conducting power being 

 lost but the irritability retained. — Prof. Gad demonstrated on 

 prepared skulls and on living animals, the curious and scarcely 

 known movements of chewing which may be observed in rats. 

 The incisors of the lower jaw are capable of lateral movement 

 in two halves united together by ligaments, and the larger part 

 of the work done in gnawing is carried on by means of the 

 scissor-like movement of the two incisors. The above has 

 recently been very fully brought to notice by Kiinstler. 



BOOKS, PAMPHLETS, and SERIALS RECEIVED. 



Reports of Geological Explorations during 1885-86-87 (New Zealand). — 

 Syst^me Silurian du Centre deS la? Boheme, vol. vii. Part i, Cystidees;: J. 

 Barrande (Prague). — Watt's Dictionary of Chemistry, vol. i. : Morley and 

 Muir (Longmans).— A Treatise on Electricity and Magnetism, vol. ii. : 

 Mascart and Joubert, translated (De La Rue). — Elementary Chemistry; 

 W. S. Fumeaux (Longmans). — Natural Laws and Gospel Teachings : Rev. 

 H. W. Morris (R.T.S.).— Early Prose and Poetical Works of Taylor, 

 the Water Poet (Hamilton). — Noctes Ambrosianse : Prof. J. Wilson 

 (Hamilton). — First Lessons in Geometry, 2nd edition : B. H. Rau (Madras). 

 — Abhandlungen der k. b. Gesellschaft der Wissenschaften Math. Naturw. 

 Classe, vii. Folge, i J3and(Prag). — Perforated Stones from California : H. W. 

 Henshaw (Washington). — Work in Mound Exploration of the Bureau of 

 Ethnology : C. Thomas (Wa.shington). — Education in Bavaria : Sir P. 

 Magnus (New York). 



CONTENTS. PAGE 



South Kensington Science Teaching 553 



Experimental Researches on Hydraulic Cements. 



By Prof. W. N. Hartley, F.R.S 554 



Elementary Microscopical Examination 555 



Our Book Shelf :— 



Mallet: " A Manual of the Geology of India " . . . 556 



Little : " Through the Yang-tse Gorges " 556 



Sloane : " Home Experiments in Science " 556 



Letters to the Editor .- — 



Prof. Rosenbusch's Work on Petrology. — Prof. T. G. 



Bonney, F.R.S 556 



The Delicacy of the Sense of Taste.— E. H. S. 



Bailey and E. L. Nichols 557 



The Salt Industry in the United States. — George P. 



Merrill • 558 



Force, and Newton's Third Law. — Dr. Oliver J. 



Lodge, F.R.S 558 



The New Photographic Objective. — Prof. Edward 



C. Pickering 558 



Life of Fleeming Jenkin. — Robert Louis Steven- 

 son 559 



The Hittites, with Special Reference to very Recent 



Discoveries. III. {Illustrated.) By Thomas Tyler . 559 

 Practical Education. By Charles G. Leland . . . 562 



Telegraphs in China 564 



Flora of the Bahamas. By W. T. Thiselton Dyer, 



C.M.G., F.R.S.; Baron Eggers 565 



Notes 566 



Our Astronomical Column : — 



The Paris Catalogue 569 



Astronomical Phenomena for the Week 1888 



April 15-21 569 



Geographical Notes 570 



Our Electrical Column 570 



Pendulum Seismometers. {Illustrated.) By Prof. 



John Milne 570 



The Cultivation of Oysters 572 



Scientific Serials 572 



Societies and Academies ' 573 



Books, Pamphlets, and Serials Received 576 



