142 



NATURE 



[yuneS, 1876 



perceived as separate impulses is the same ; so, too, with the 

 number at which beats and primary impulses pass into a tone. 

 Intermittences of a tone, as well as beats and primary im- 

 pulses, may pass into a tone, and the periodic maxima of vibra- 

 tion of a tone, when in sufficient number. The beat tone formed 

 by two primary tones must be always weaker than these, though 

 separate beats are stronger than the tones forming them. — In M. 

 Grotrian's researches on the constants of friction of some salt solu- 

 tions, and their relations to galvanic conductivity, the method for 

 ascertaining the constants was that of observing the oscillations of a 

 suspended disc with attached magnet (under the influence of a neigh- 

 bouring magnet) in air and in the liquid examined. The observed 

 generally similar course of temperature coefficients for fluidity and 

 galvanic conductivity, with change of concentration, leads the 

 author to conclude that the overcomingof internal friction forms an 

 essential part of the work done by a current in passage through 

 an electrolyte. In the case of chloride of potassium, it is found 

 that the increase of conductivity is almost exactly proportional 

 to the per-centage proportion (in the liquid) ; and M. Grotrian 

 infers that the chemical changes he conceives generally to occur 

 in chemical constitution of electrolytic molecules, on altering the 

 concentration, do not occur here, but that with varied concentra- 

 tion, at the same temperature, the conductivity is only condi- 

 tioned by the proportion of salt and the viscosity. With the 

 numbers obtained in the experiments, it is possible to estimate for 

 variously concentrated solutions of a salt, the temperatures for 

 which the constants of friction have some determinate constant 

 value ; then to calculate the numbers for the conductivity at this 

 temperature, and inquire according to what law these alter with 

 the concentration. He thus shows that in the case of NaCl, 

 KaCl, CaCh,, and BaClg, the concentration and the viscosity are 

 the principal factors which determine the amount of the conduc- 

 tivity. — In the next paper M. Wiedemann makes some adverse 

 criticism on the recent researches of some French physicists in 

 the domain of magnetism. — M. Holtz shows that wire-net is 

 very well suited for proving that in the interior of conducting 

 surlaces there is no electrostatic action. In one experiment, a 

 bell-shaped cover, made of the net, is brought down by an insu- 

 lating handle on an insulated metallic disc connected with an 

 electric machine, and on which stands a pith-ball electrometer. 

 The two balls do not diverge in the least on working the 

 machine ; but if the bell be removed, they do so at once. He 

 shows further, how such a bell is like a filter or sieve, holding 

 back the electricity while it affijrds partial passage to gaseous 

 matter or dust. If a metallic point connected to earth be 

 brought near the electrified bell, the balls are moved, but do 

 not diverge, &c. — Dr. Wichmann studies the properties of 

 doubly-relracting garnets ; and we note a paper by Dr. Sohncke 

 on the figures eaten out by dissolving liquids on blocks of rock 

 salt, and Exner's method lor producing solution- figures. — There 

 is an account of an interesting inquiry, lately conducted by Dr. 

 W. Siemens, on the velocity of propagation of electricity in 

 suspended wires. 



/Proceedings of the Geological and Polytechnic Society of the West 

 Riding of Yorkshire, New Series. Part 2. Pp. 57 to 112. — This 

 part contains several very interesting papers on various points of 

 local geology. Some of the papers will be of use to a wide circle 

 of readers, such as Mr. C. Bird's on the red beds at the base of 

 the carboniferous limestone in the north-west of England, and 

 Prof. Green's on the variations in thickness of the Silkstonc and 

 Barnsley coal seams in the southern part of the Yorkshire coal- 

 field, and the probable manner in which these and similar 

 changes have been produced. Mr. Bird considers it better to 

 regard the red beds in question as basement beds of the carbo- 

 niferous limestone than to attempt to draw any arbitrary line in a 

 series whose members appear so closely linked together. Mr. 

 Tiddeman's concise account of the work and problems of the 

 settle Victoria cave exploration will also be welcome. Five good 

 plates accompany this number of the Proceedings. 



Bulletin de V Academic Royale des Sciences, 2 ser. tome 40, No, 

 12. — M. van Beneden contributes a long paper divided into six 

 chapters on the early stages of the embryological development 

 of mammals. In 1874 M. Beneden published his paper, in 

 which he showed that in Hydractinia spermatozoids are derived 

 from the ectoderm and ova from the endoderm. He suggested 

 that the same law probably applied to vertebrata. Observations 

 supporting his view with regard to Ccelenterata have been made 

 by Koch and Fol, and M. Beneden has made embryological 

 studies on the rabbit. A monograph with plates is promised. 

 This paper is a resume.— Qxv the skeleton of a fossil whale in 



the museum at Milan, by P. J. van Beneden. Following up the 

 descriptions of Pachyacanthus and Aulocetus already given, M. 

 Beneden proceeds to describe the fossil found in 1806 at Mount 

 Pulgnasco, preserved in the Milan Museum, figured by Cortesi 

 and described by Cuvier. The description is accompanied by a 

 plate, and there are references to fossil whales in the museums at 

 Turin, Florence, Bologna, Parma, and Pisa. — On the period of 

 cold of the month of December, 1875, by M. E. Quetelet. — On 

 the Devonian sandstones of Condroz, in the Ba-in of Theux, in 

 the basin between Aix-la-Chapelle and Ath, and in the Boulon- 

 nais. The paper is illustrated with a folding plate giving nine 

 coloured sections, and its scope is to show that the beds of the 

 different localities mentioned have the same relative stratigraphi- 

 cal relations as at Condroz. All of the subdivisions show a 

 remarkable constancy in their petrological and palseontologica 

 aspects. — On the description of some new birds, by M. Alph. 

 Dubois. They belong to Cyanscitta and Icterus. — The theory 

 of carnivorous and sensitive plants, by E. Morren. The article 

 is a /-CJ-wwi? of observations that have been made, and is well 

 furnished with foot-notes. The index accompanies this number. 



SOCIETIES AND ACADEMIES 



London 



Royal Society, May 18.—" Observations on Stratified Dis- 

 charges by means of a Revolving Mirror, by William Spottis- 

 woode, M.A., Treas. R.S. 



In a paper published in Poggendorff''s Annalen, Jubelband, 

 p. 32, A. WUliner has described a series of observations made, 

 by means of a revolving mirror, upon the discharge of a large 

 induction-coil through tubes containing ordinary atmospheric 

 air at various degrees of pressure. 



Wiillner's observations appear to have been directed rather to 

 the nature of the coil discharge than to that of the stratifications. 



For some time prior to the publication of the volume in ques- 

 tion I had been engaged upon a series of experiments very 

 similar in their general disposition, but with a somewhat different 

 object in view, viz., the character and behaviour of the striae ; 

 and of these, together with some recent additions, I now pro- 

 pose to offer a short account to the Society. 



My general instrumental arrangements appear to have been 

 similar to those of Wiillner ; in fact, they could hardly have been 

 very different. The tubes were attached to the coil in the usua.1 

 way, and a contact-breaker of the ordinary form with its own 

 electro-magnet was in the first instance used. For this and some 

 other intermediate forms there was finally substituted a mercu- 

 rial break (successfully arranged by my assistant, Mr. Ward), 

 the plunger of which works on a cam attached to the axle of the 

 mirror, so that the action of the contact-breaker is regulated by 

 that of the mirror, instead of the reverse as in the former arrange- 

 ment. With the broader tubes a slit was used ; with the nar- 

 rower this adjunct was less necessary ; while with capillary tubes, 

 such as are used for spectrum-analysis, it could be dispensed with 

 altogether. 



Striae, as observed by the eye, have been divided into two 

 classes, viz., the flake-like, and the flocculent or cloudy. Of the 

 former, those produced in hydrogen tubes may be taken as a 

 type ; of the latter, those produced in carbonic tubes. But upon 

 examining some tubes especially selected for the purpose, it was 

 found that, while to this apparent a real difference corresponds, 

 a fundamental feature of the striae, underlying boih, was brought 

 out. 



The feature in question was this : that the striae, at whatever 

 points produced, always have during the period of their exist- 

 ence a motion along the tube in a direction from the negative 

 towards the positive terminal. This motion, which I have called 

 for convenience the proper motion of the striae, is for given cir- 

 cumstances of tube and current generally uniform ; and its varia- 

 tions in velocity are at all times confined within very narrow 

 limits. The proper motion in this sense appertains, strictly 

 speaking, to the flake-like stride only. The apparent proper 

 motion of the flocculent striae is, on the contrary, variable not 

 only in velocity, but also in direction ; and on further examina- 

 tion it turns out that the flocculent striae are themselves com- 

 pounded of the flake-like, which latter I have on that account 

 called elementary strice. 



Elementary striae are in general produced at regular intervals 

 along the tube. The series extends from the poiiiive terminal 

 in the direction of the negative to a distance depending upon 

 the actual circumstances of the tube and current. The length of 



