6o8 



NATURE 



[Oct. 3, 1878 



is commonly supposed, an electric discharge in a rarefied gas, 

 it must admit of a very considerable range of density, since it is 

 certain that even in the same aurora, different portions are at 

 very different elevations. In the crown for instance, the beams 

 are almost perpendicular, and must be often of very great length. 



The aurora has frequently been supposed to be a sign of 

 coming wind and stormy weather, but careful comparison of the 

 meteorological records failed to establish any such connection. 

 No sound could be attributed to the northern lights. 



Weyprecht's observations confirmed the fact that there is a 

 zone of maximum frequency and intensity of anrorse some dis- 

 tance south of the pole, and led further to the conclusion that 

 the zone moves northward towards the winter solstice, and south- 

 ward again towards the equinoxes. It is of course impossible 

 to observe its course during the summer. 



Observations of the daily period gave a maximum at 10 P.M., 

 and a minimum at II A.M., which closely coincides with the 

 results of other observers. 



No very clear conclusion could be drawn as to a yearly period, 

 since the length of the nights, the cloudiness of the sky, and 

 above all, the before-mentioned shifting of the zone of maxi- 

 mum frequency so complicated the problem. 



Want of space unfortunately forbids us to enter into any 

 detailed discussion of Weyprecht's extensive magnetic obser- 

 vations. Many magnetic disturbances were unaccompanied 

 by aurora, and on the other hand, some avirora produced little 

 or no magnetic variation. Those appearances which have an 

 indistinct outline and diffused light, and especially which have 

 no rays and and no noticeable motion, scarcely affect the needle ; 

 while, on the contrary, those which appear to be low and near, 

 which have distinct contour and rapid motion, and above all 

 sharply defined rays, affect the needle vigorously. Broad 

 darting lightning-like rays, with brilliant colours, red and green, 

 cause the most violent disturbances. Henry R. Procter 



UNIVERSITY AND EDUCATIONAL 

 INTELLIGENCE 



We are pleased to find that local schools of science are in- 

 creasing their facilities for teaching practical chemistry to their 

 students. During the summer the committee of the Birkbeck 

 Institution (the first London Mechanics' Institute) has built a 

 new chemical laboratory, to replace the somewhat inconvenient 

 one which has done service for fifty years. The space available 

 was very limited, but has been made the most of, and nineteen 

 benches have been fitted up in a space of 36 feet by loi feet 

 besides the necessary accommodation for stores, &c. This effort 

 to meet the requirements of students is all the more commend- 

 able, on account of the probability of the Institution remaining 

 but a few years longer in its present home. Its success is so 

 great that a new and larger building is absolutely necessary, and 

 the building fund being raised amounts already to nearly a 

 thousand pounds. 



SOCIETIES AND ACADEMIES 

 Paris 

 Academy of Sciences, September 16.— M. Fizeau in the 

 chair. — The following papers were read :— On the cause 

 of the periodic movements of flowers and leaves, and on helio- 

 tropism, by M. P. Bret.— On a new telephonic transmitter, by 

 M. P. Dupont. — Remarks on a new proposal made with regard 

 to the analysis of milk, by M. E. Marchand.— Description of 

 a new apparatus for the transfer of gases from one vessel 

 to another, by M. A. Blanc. The appatatus is constructed 

 with the special view of avoiding any loss of gas on its 

 being transferred over mercury.— Various communications re- 

 garding phylloxera, by MM. E. Fortierand Capbladoux.— Onthe 

 Jntra-Mercurial planet seen in the United States during the solar 

 eclipse of July 29 last, by Mr. Swift.— On the observations made 

 of the transit of Mercury on May 6, 1878, at the Imperial Ob- 

 servatory of Rio de Janeiro, after the new method, by M. Emm. 

 Liais.-On the form of the integrals of differential equations of 

 the second degree in the neighbourhood of certain critical points. 

 —On the compressibility of gases at high pressures, by M. E.' 

 H. Amagat.— New researches on the physiology of the vesicular 

 epithelium, by MM. P. Cazenove and Ch. Lyon.— Note on the 

 interior temperature of the globe, by Mr. W. Morris.— Note re- 

 lating to an apparatus named galioscope, by M. A. Boillot. 

 i. nis apparatus is constructed to demonstrate the invariability of 



the direction of the plane of oscillation of a pendulum. — Note 

 relating to a new thermohydrometer, by Mr. H. Douglas. 



September 23. — M. Fizeau in the chair.— The following 

 among other papers were read : — Dissociation of oxides of the 

 family of platina, by MM. Saint Claire Deville and Debray. 

 Osmium and ruthenium combine directly with oxygen, and the 

 product of oxidation is volatile and forms at the highest tempera- 

 tures. In this they are distinct from the other platinic metals, 

 and come near arsenic and antimony, with which they might be 

 placed among the metalloids. From experiments with oxide of 

 iridium the authors show that, at a temperature below 1003*3°, 

 it is decomposed in free air, and consequently that, at this tem- 

 perature or any other higher, iridium is absolutely inoxidable in 

 the air. — Memoir on a universal law relative to the dilata- 

 tion of bodies, by M. Levy. This is designed to prove 

 that the pressure which any body supports can only be 

 a linear function of its temperature, so long as this body 

 does not change its state; in other words, and under a 

 physical form, if any body be heated with constant volume, 

 the pressure which it exerts on the immovable walls of the 

 inclosure containing it, can only increase, rigorously, in propor- 

 tion to its temperature. This, he thinks, an absolutely rigorous 

 corollary from the two fundamental propositions of the mechanical 

 theory of heat, and of the hypothesis that the mutual actions of 

 the atoms of bodies are directed in lines which join their points 

 of application, and only depend on the distances of these points 

 apart. — Nocturnal variations of the temperature at different alti- 

 tudes recorded at the observatory of Puy-de-D6me, by M. 

 Alluard. He has traced, for each month since January, the 

 ciu-ves of minimum, maximum, and mean temperatures of the 

 two stations, and it appears that the two curves of minimum 

 temperature often cut each other, both in summer and in 

 winter, so that, often, at night, it is less cold at the top 

 of the Puy-de-D6me than at Clermont, the difference 

 sometimes reaching five degrees. The curves of maxi- 

 mum temperature do not intersect ; they are in general 

 nearly parallel. The temperature at night, then, varies with the 

 height, quite otherwise than during the day. A new meteo- 

 rological station has been formed about midway between Cler- 

 mont and the summit of Puy-de-D6me, the three heights being 

 thus— 400 m., 1,000 m., and 1,470 m. It is purposed, too, to 

 take observations on some of the numerous extinct volcanoes 

 (in form of truncated cones) about the Puy-de-D6me, the object 

 being to study the atmosphere, layer by layer. — Discovery of a 

 small planet at the observatory of Hamilton College, Clinton, 

 by Mr. Peters. — On a new species of curves and of anallag- 

 matic surfaces, by M. Picquet. — On the development of chilo- 

 stoman bryozoa, by M. Barrois. This he finds mesoblastic, the 

 exoderm gives rise to all the oi^ans and plays the part of a 

 veritable blastoderm. — M. Lancy presented a work by M. 

 Ennes, surgeon in die Portuguese army, on "Men and Books 

 of Military Medicine." 



CONTENTS p^cB 



Dobson's Catalogue of Bats , . -sg 



Tidy's " Handbook of Chemistry " '.'..'..'. 586 



Letters to thb Editor :— 



On the Proposed Observatory on the Summit of Mount Etna.— 



G. F. RODWELL C87 



Compound Lightning Flashes.— E. H. Pringle ...'.!!". 587 



Gyno-Dioecious Plants.— Thomas Whitelegge 587 



Wasps under Chloroform. — W. M 588 



" Mercator " the Geographer. — J. C. G - . .' 588 



Our Natural History Collections.— E. H .588 



Our Astronomical Column :— 



Biela's Comet 588 



Encke's Comet !!! 589 



Brorsen's Comet t ..'.'.'.'. ', 580 



New Minor Planets * egg 



Augustus Heinrich Petermann 589 



The Norwbgian North Atlantic Expedition By Dr. H. Mohn. 590 



Dr. Schliemann on the Ancient Capital of Ithaca ego 



Are the "Elements" Elementary? By M. M. Pattison 



MuiR .52 



On the Nature of Vibratory Motions, II. By Prof. Alfred 



Marshall Mayer {With Illusirations) 594 



On an Ascent of Mount Hekla, and on the Eruption of 

 February 27, 1878. By G. F. Rod\vbi.l {WiiA /l/us/raiion) . . 596 



Notes jgs 



The Figure AND Size OF the Earth, III. (^FzVA ///w/ra/ZiJw) . . 603 

 An Experimental Investigation of the Structure of Fluid 

 Columns which are Affected by Sound. By R. H. Ridout 



(IViik Illustrations) 604 



The Aurora Observations of the Austro-Hungarian Arctic 

 Expedition, 1872-74, by Carl Weyprecht. Henry R. Procter 6c6 



University and Educational Intelligence 608 



Societies and Academies 608 



