622 



NATURE 



[OCTOBEK 25, 1894 



I 



In a paper contributed to L'Eclairage EUclriquc, Signor L. 

 Palmieri gives an account of the results he has obtained 

 during the last few years in his study of the earth-currents 

 at the Vesuvius Observatory. One of the earth-lines used 

 tenninaies in a large copper plate buried in a well at the 

 little village of Rcsina at the base of the mountain, and 

 follows the direction S.W.-N.E. to the Observatory, where it 

 is taken almost vertically down from the observing room 

 and connected with the lightning-conductor. A shorter line 

 has been tried in several azimuths, but has finally been per- 

 manently fixed in aX.W. direction from the Observator)-. At 

 first an ordinary astatic galvanometer with rather long magnetic 

 needles was used, but it was found that the powerful currents 

 which passe<l during thunderstorms often demagnetised the 

 needles, or even magnetised them in the reverse direction. The 

 ordinary form of suspended coil D'Arsonval galvanometer was 

 also found to be subject to the objection that if the metallic 

 suspension was sufficiently fine to allow of the small currents 

 ordinarily obtained being recorded, then the large currents some- 

 times obtained fused the suspension. Finally the author, after 

 consulting with Marianini, designed an instrument which 

 es<;entially consists of a small electro-magnet the coils of which 

 are connected to the earth-line and a magnetised needle 

 suspended above this magnet. After more than a year of con- 

 tinuous observation, the author had come to the conclusion that 

 the earth-cutrents were always from the lower station to the 

 higher ; but towards the end of August 1893, the currents com- 

 menced to vary in direction, and finally settled down in the 

 opposite direction to that they had taken since 1889, when ob- 

 servations were first started. The change in the direction in 

 the earth-currents occurred at a period when the volcano was 

 more than usually active ; but in January and February 1894 

 the volcano became much less active, and the earth-currents 

 first decreased in intensity and then resumed their old upward 

 direction. The activity, however, broke ou'. again, at the 

 central crater this time, and the earth-currents again changed 

 their direction. In every case it has been found that when the 

 volcano is quiescent the earth-currents ascend, but when the 

 volcano's activity increases, the earth-currents at once change 

 their direction and pass from the higher station to the lower. 

 On June 7, 1891, when the lava made its first appearance, it 

 was noticed that the needle of the astatic galvanometer at that 

 lime employed was continually in movement ; and this move- 

 ment was very irregular, the needle often behaving as if it had 

 received a sudden blow. 



A BRIEF summary of the analytical work required for the 

 practical examinations in inorganic chemistry of the Science 

 and Art Department is given in "A Laboratory Guide and 

 Analytical Tables," by Mr. James Grant (Smith and Wood, 

 Manchester). 



The October number of the Proceedings of the Physical 

 Society of London (vol. xiii. part i.) has been published. It 

 contains thirteen papers and six plates. The Journal of the 

 Royal Microscopical Society, for October, has also just been 

 isiaed. 



Messrs. Williams and Norcatb have issued the sixtieth 

 number of their scientific book circular, in which are catalogued 

 new scientific publications, mostly of foreign origin, offered for 

 *alc by them. A similar catalogue has been received from Mr. 

 J. H. Knowlef, Lavender-hill, London, S. W. 



The Ettctrician Printing and Publishing Company are just 

 issuing " Electric Lamps and Electric Lighting," by Dr. J. A. 

 Fleming, F.R..S. The same publishers also announce, as ready 

 shortly, "Electric Motive Power," with chapters specially 

 dealing with the use of electricity in mines for lighting, 

 haulage, pumping, coal-getting, &c. This latter work is by 

 Mr. Albion T. Snell. 



NO. 1304. VOL. 50] 



Under the title " Regularisation des Moteurs des Machines 

 Electriques," M. P. Minel has completed a series of four 

 volumes, which he has written for the Encyclopedic scientilique 

 des Aide-Mtmoire, on electricity and its applications to 

 navigation. This new work has recently been published by 

 MM. Gauthier-Villars, and also a volume on " Fortification," 

 by Lieut. -Colonel Hennebert. 



Mr. Elliot Stock has published a cheap edition of " A 

 M.anual of Exotic Ferns and Selaginella," by Mr. E. S.indfoid. 

 The book comprises descriptions of more than one thousand 

 species and varieties, and upwards of si,v hundred synonyms, 

 as well as notes on the history, culture, and management of the 

 plants considered. Amateur, and also professional, horticul- 

 turists will find the volume useful. 



The Geographical and Geological Commission of Sao Paulo, 

 Brazil, has for some years published useful climatological data 

 for that province. The last we have received is for the year 

 1892, and contains monthly and yearly means for twelve 

 stations, and also for Rio de Janeiro, with a good general 

 discussion, of the data for each place, by Sr. Schneider. .Vs 

 this State forms part of the cofiee-growing region of Brazil, 

 the publication of these summaries is of interest, both from 

 scientific and commercial points of view. 



Four lectures on biology, delivered by Dr. R. W. Shufeldt, 

 before the Catholic University of America, in January 1892, 

 have been reprinted from the American Field, and published 

 in pamphlet form. The lectures deal iwith the history and 

 present domain of biology ; the relation of biology to geology ; 

 the value of biological study ; and the growth and future in- 

 fluence of biology. They caused considerable stir at the time, 

 for Dr. Shufeldt did not mince matters in presenting an 

 account of the bearing of Catholicism to early scientific in- 

 vestigation. Nothing can be found in them, however, that is 

 not sustained by the best of evidence. 



Dr. Bkla Haller has revised his numerous researches upon 

 the morphology of Prosobianchiate molluscs, and has incorpora- 

 ted them in the form of a handsome quarto monograph entitled 

 " Studien iiber Uocoglosse und Rhipidoglosse Prosobranchier 

 nebst liemerkungcn liber die phyletischen Beziehungen der 

 Mollusken untereinander," published i)y Engebuann, of Leipzig. 

 The student of molluscaii morphology will find there a lucid and 

 .idniirably illustrated exposition of anatomical data, and will 

 not fail to be stimulated, if only to opposition, by Haller's 

 peculiar views on the phylogeny and inter-relations of the 

 different molluscau groups. 



EviCRV student of physical chemistry unfamiliar with the 

 German language will welcome a " Manual of Physici-Cliemic ' 

 Measurements " (Macmillan and Co.), translated by Dr. James 

 Walker from Prof. W. Ostwald's standard work. The German 

 edition was reviewed in these columns at the beginning of 

 this year (Naturk, vol. xlix. p. 219), and it was then remarked 

 that the manual was the only guide to measurements in physical 

 chemistry suitable for service in the laboratory. The book is 

 not intended for the beginner, but for the chemist and physicist 

 who desires to become iiraclic.illy acciuainted with the region 

 common to both of them. Dr. Walker's .idmir.iblc translation 

 will doubtless considerably increase the sphere of usefulness of 

 Prof. Ostwald's work. 



A SECOND edition of the laic Thomas Laslett's classical 

 work on "Timber and Timber Trees" (Macmillan and Co. 1, 

 completely revised, with numerous additions and alterations, 

 by Prof. Marshall Ward, has just been published. The arrange- 

 ment of the work has been completely altered, and the numerous 

 advances that have been made in our knowledge of timber 



