January 17, 1901] 



NA TURE 



283 



The pamphlet, short though it is, contains many suggestive 

 results, and we await with interest the promised account of 

 further experiments. 



In the Physical Review, xi. 5, Mr. W. P. Boynton gives an 

 investigation of the form of Gibbs' thermodynamic model for a 

 substance following Van der Waals' equation, and compares 

 this model with that given by Maxwell. 



Prof. Antigono Raggi, writing in the Rendiconti del R. 

 Istituto Lombardo, xxxiii. 17, gives a summary of the works of 

 Serafino Biffi, who died on March 27, 1899. Bififi was the 

 author of many valuable contributions to medical and physio- 

 logical science, and we are glad to learn that his collected 

 works are shortly to be published. 



A PKYSiCAi. theory of nerve is given by Mr. W. M. Strong 

 In the Journal of Physiology (xxv. 6). The theory, which is 

 based on the ionic theory of salt solution, assumes all nerves to 

 consist of a semi-solid axis cylinder containing a saline sub- 

 stance in solution. The salt is wholly or partially ionised, so 

 that the axis cylinder is a good electrolytic conductor. Sur- 

 rounding it is a medullary sheath or outer layer formed of a { 

 relatively bad conductor. The negative ion of the salt is sup- 

 posed to be of a simple nature and to move freely in the semi- 

 solid material of the axis cylinder, while the positive ion only 

 moves with great difficulty. The contraction of a muscle, the 

 author supposes, is directly caused by the arrival of the negative 

 variation at the point where the nerve terminates in the muscle. 



The tenth volume of scientific memoirs edited by Prof. H. 

 Crew and published by the American Book Company, contains 

 reprints of the more important treatises dealing with the " wave 

 theory of light." Beginning with the work of Christian Huy- 

 gens, the first three chapters of his " Treatise on Light " {1678) 

 are given, describing rectilinear propagation, laws of reflection 

 and refraction ; concluding this section is a biographical sketch 

 of the life of Huygens. Next are given three of the historical 

 contributions of Dr. Thomas Young, on the ' ' Theory of Light 

 and Colours," "On the Production of Colours," and " Experi- 

 ments and Calculations in Physical Optics," followed, also, by a 

 short biographical sketch of the author. The volume is con- 

 cluded by memoirs of Arago and Fresnel on the " Diff"raction 

 of Light" and "Action of Polarised Light," a biography of 

 Fresnel, and a bibliography of the literature at present available 

 on the subject. 



We have received a copy of a report on Hertzian waves 

 ■drawn up for the recent Physical Congress at Paris by Prof. 

 Augusto Righi, of Bologna. The report deals with the subject 

 from two points of view ; the theoretical aspect, which considers 

 the physical identity of Hertzian waves and waves of light, and 

 the practical aspect in connection with wireless telegraphy. 

 Prof. Righi's paper is divided into four sections, the first con- 

 taining a description of the apparatus used in connection with 

 the production and study of Hertzian waves, the second with 

 radio-conductors, the third with the optical properties of elec- 

 trical oscillations, and the last with Hertzian telegraphy. Prof. 

 Righi's intimate knowledge of the subject and the important 

 part he himself is known to have played in connection with the 

 invention of wireless telegraphy have eminently qualified him 

 for furnishing physicists with a brief summary of the progress 

 made in this branch of physics since it was first opened up by 

 Hertz. 



The December number of the Photo-Era, the American 

 journal of pho tography, contains many articles of interest. Mr. 

 Yellot reviews the third " Philadelphia Photographic Salon," 

 and evidently does not think very much of it, as he talks of the 

 ..." dreary monotony about the tier on tier of weak, fuzzy, 

 NO. 1629, VOL. 63] 



washed-out-looking photographs. ..." Landscape compo- 

 sition is another communication worth perusing. Under the 

 heading "Photographing the Aurora," Mr. Stiles describes 

 and illustrates the photograph he obtained at Mount Washing- 

 ton. He used a Ross-Goerz six-inch lens, aperture 77, and 

 isochromatic plates, and gave an exposure of 35 minutes. 

 He writes : " What is surprising is the actinic power of the 

 auroral light as compared with the bright moonlight on the 

 snow. Under the aurora is a dark space, which is noted in 

 many displays. This in earlier notes on the aurora was assumed 

 to be dark by contrast, but the photograph shows a quite definite 

 lower boundary." 



We have received from St. Xavier's College Observatory the 

 monthly meteorological results for the months of January to 

 June for the thirty-three years 1868-1900, which we are glad 

 to see will shortly be followed for the other six months, ending 

 December last. The observatory was established in August 

 1867, and is situated one and a half miles north-east of the 

 Alipore Observatory, and is sufficiently isolated for trustworthy 

 observations. The instruments have been compared with those 

 at either Kew Observatory or the Government Observatory at 

 Alipore, and the observations have been carefully taken several 

 times daily by the fathers in charge, so that the tables form a 

 a very valuable series. 



Messrs. Elster and Geitel have sent us 'some further 

 accounts of their interesting experiments on atmospheric elec- 

 tricity. In No. 8, vol. ii. of the Physikalische Zeilschri/l, 

 papers are communicated on the measurement of electrical leak- 

 age in free air, and in closed spaces. Dr. Geitel finds that 

 with regard to the air in a closed vessel, with an initial charge 

 of 240 volts (independently of the sign of electrification) the 

 leakage from an insulated body amounted to about 0*4 per cent, 

 per minute ; on the second day the leakage amounted to i 'o per 

 cent., and on the fourth day to i'4 per cent. After this period 

 the leakage became slower, and gradually attained a limit of 

 about 2 per cent, per minute. A full description is given of the 

 apparatus employed. He also found that the leakage was not 

 proportional to the charge of electricity, but that for charges 

 varying from 80 to 240 volts the amount remained constant. 

 This phenomenon was pointed out by Matteucci in 1850 

 {Annales de Chdmie et de Physique, vol. xxviii. ), but the observa- 

 tion remained practically unnoticed. Further, Dr. Geitel 

 found that the influence of daylight, or of artificial illumination, 

 was not perceptible on the results obtained. 



The new number of the Abhandltmgen of the Vienna 

 Geographical Society consists of an exhaustive paper on the 

 cork-tree, by Eugen Miiller. The botany of the cork-tree and 

 the growth and chemical constitution of the cork are first dis- 

 cussed ; then follow a lengthy investigation of the geographical 

 distribution of the cork-tree, a history of the production of cork, 

 and a statistical account of the development of the world's trade 

 in cork. 



Prof. Mitzopulos contributes a paper on two of the most 

 remarkable of the seismic disturbances experienced in Greece 

 during the years 1898 and 1899, to Peter manns Mitteilungen. 

 The first, the Tripolis earthquake of June 2, 1898, Prof. Mitzo- 

 pulos believes to have been caused by subterranean falls of rock. 

 The second, or Triphylia earthquake, occurred on January 22, 

 1899 ; its epicentrum is located in the Ionian Sea, some 35 to 

 40 kilometres to the west of the coast of the Peloponnesus, 

 where the bottom goes down in terraces to depths of 2500 to 

 3500 metres. The epicentrum was probably about 70 kilometres 

 below the sea-bottom. 



The greater part of the December number of the National 

 Geographic Magazine is devoted to an account, by Mr. Wilbur C. 



