May 9, 1895] 



NA TURE 



35 



zoologists have promised to attend the meeting, and to deliver 

 addresses or read papers. The following scheme for the sectional 

 meetings has been arranged :— ( I ) Cieneral zoology ; geographical 

 distribution, including the fossil faunas ; the theory of evolu- 

 tion. (2) Classification of living and extinct vertebrates ; 

 bionomy ; geographical distribution, including fossil vertebrates. 

 (j) Comparative anatomy of living and extinct vertebrates; 

 embryology. (4) Classification of living and extinct invertebrate 

 animals ; bionomy. (5) Entomology. (6) Comparative anatomy 

 and embryology of invertebrate animals. Intending members 

 may send the subscription (;^l) to Dr. 1". P. C. Hoek (Helder), 

 tiie General Secretary, or to Dr. R. Horst (Leyden), Treasurer. 



The summer meetings of the Institution of Naval Architects 

 will be held in Paris on Tuesday, June 11, and during the 

 remainder of the week. The Right Hon. Lord Brassey, K.C.B., 

 President of the Institution, will occupy the chair. We are 

 informed that the French Government is taking a warm interest 

 in these meetings, and that, under the honorary presidency of the 

 Minister of Marine, Vice-Admiral Besnard, and under the acting 

 presidency of Vice-Admiral Charles Duperre, a strong and influen- 

 tial Reception Committee has been formed, representing the 

 Ministry of Marine, the French Navy, the Municipality of Paris, 

 the Chamber of Commerce of Paris, the (Ireat French Industries 

 and Steamship Owners, the Railroad Companies, the University of 

 Paris, the Conservatoire des Arts et des Metiers, the French Insti- 

 tution of Civil Engineers, the Society for the Encouragement of 

 National Industry, the French Institution of Naval Architects, and 

 the Union of Yachts. This Committee has already taken active 

 steps to draw up a programme of exceptional interest for the 

 instruction and entertainment of the Institution. Papers have 

 already been promised by M. Emil Bertin, Director of the French 

 Government .School of Naval Architecture, and M. V. Daymard. 

 There will also be papers by .Sir William White, Mr. B. Martell, 

 Dr. Francis Elgar, Mr. .\rchibald Denny, and Mr. Mark 

 Robinson. 



DuRi.sr. the Easter vacation the following naturalists have 

 been at work in the Liverpool Marine Biological -Station at Port 

 Erin :— Dr. H. O. Forbes, Mr. F. (;. Baily, Mr. P. .M. C. 

 Kermode, Dr. J. D. Gilchrist (Edinburgh University), Mr. .\. O. 

 Walker, Prof. Herdman,and Mr. J. C. Sumner (curator). Two 

 steamer dredging expeditions have been carried out to the west 

 and south of the Isle of Man. On these a small shank trawl was 

 wurked.in addition to the dredge, with considerable advant;igc — 

 im one occasion, in fact, coming up so full that the net burst 

 with the weight on leaving the water, and the contents were lost- 

 .\ number of fine Pxhinoderms were obtained with the trawl, 

 including I.ttidca, Fabuipcs^ Porania^ StichasUr^ Synapta, 

 and other Holothurians. Amongst the Cnistacea were 

 Si-a/pe/liim, Mniiitia baiitfica, Xatttho ttiberctilata, Ebalia 

 luberosa and E. tuiiicfaila, Anapagurtis hyndtiianni, Galathca 

 dispirsa with Plfiirocrypta dispcrsa, Mclphidipclla macera. and 

 a number of the rare shrimp Fontopkiltis spitwsitSy Leach. 

 Floating fish eggs (plaice and another species) were caught in the 

 tow-nets in Port Erin Bay, both in March and April ; and Ap/ysia, 

 Doris, Sepio/a, and other Invertebrates have spawned in the 

 tanks at the Biological Station. The Liverpool Committee is at 

 present considering the possibility of a further extension of the 

 .Station in the form of a hatchery and a large tidal pond, such as 

 was contemplated in Prof. Herdman"s original scheme of the 

 institution. 



.\n Italian .Seismological Society has recently been founded by 

 Prof. Tacchini, the well-known Director of the Central Meteoro- 

 logical and Geodynamic (Jffice at Rome. Its objectsare to make 

 known as soon as possible all the seismic and volcanic phe- 

 nomena occurring either in Italy or in other countries, to publish 

 short notes about them, descriptions of seismic apparatus, cV:c., 



NO. 1332, VOL. 52] 



and generally to promote the study of geodynamics. The sub- 

 scription being moderate, anti national and foreign members 

 being admitted on nearly the same terms, the new society, it 

 to be hoped, may become practically a European one. 



.\ tJSEKUl. innovation, that we hope is to be continued, has 

 been started by the Geological Society of London, in the 

 publication of a catalogue of geological literature added to the 

 .Society's library during the half-year ended December 1894. 

 This is etjuivalent to a list of all important books and jrapers on 

 geology published in that period. Every i>aper is catalogued 

 separately, under the author's name, and there Ls a subject-index. 

 The whole is a distinct improvement on the list hitherto published 

 annually in the November Quarterly Journal : and in spite of the 

 improvements, this list for the half-year is le-ss than half the bulk 

 of the last annual one. The only important omission is that of 

 maps. The work will be most useful to all geologists who wish 

 to keep abreast of recently published works. 



The science of oscillations has been enriched by some simple 

 and instructive elementary experiments, due to Dr. H. J. Costing, 

 which are described in the Zeitsihrift fiir den Physikaiischen 

 Unterruht. That the velocity of a pendulum is greatest when 

 the bob reaches its mean position is shown by means of a pen- 

 dulum with a mirror attached to it at its axis of suspension, the 

 upper end of the pendulum-rod being attached to a stout wire 

 bridge, the feet of which take the place of the knife edge. \Vlien 

 a beam of light is reflected from this mirror, a line of light is 

 formed upon the screen if the pendulum vibrates rapidly enough. 

 The light from the lamp is made intermittent by a uniformly 

 revolving disc provided with holes tared at equal intervals near 

 the edge. A series of points are then produced on the screen, 

 which are crowded together towards the ends, and further apart 

 towards the middle of the line of light, the distance being pro- 

 portioned to the velocity of the bob. 



Another neat contrivance designed by the Dutch physicist 

 is one for producing Lissajou's curves resulting from the com- 

 bination of two vibrations at right angles to each other. The 

 simplest form of vibrating mirrors consists of two small mirrors 

 attached to wires stretched in a vertical and horizontal position 

 respectively. The (leriods of vibration are adjusted by screws 

 carrjing nuts mounted behind the mirror at right angles to the 

 wire. The vibration is made slower by .screwing the nuts out- 

 wards ; or, if a penduluni is to be used, it is attached to the 

 bottom of a U-shaped wire bent out and down at the upper 

 ends, so as to oscillate about the ends of the wire. -\ horizontal 

 circle is attached to the U at the centre of suspension, carry- 

 ing a precisely similar suspension for a second and smaller pen- 

 dulum, except that a horizontal mirror takes the place of the 

 horizontal circle. The periods are adjusted by weights movable 

 along the rods, and the resulting curves may be thrown ujmu 

 the ceiling, or back upon a screen just in front of the lantern 

 with a hole for letting the light through. In this ca.se the beam 

 must be twice reflected from a mirror at 45" to the horizon. 



Within the last year or two, the number of methods for 

 obser\-ing the characteristics of an alternating current which have 

 been described is considerable. The latest step in this direction 

 is due to M. J. Pionchon (Comples rcndns, April 22, 1S95), who 

 uses an optical method. The alternating current is passed 

 through a coil, surrounding a tube filled with carbon bisulphide 

 or a saturated solutiim of mercuric and potassium iodides. This 

 tube is jilaced between the polariser and analyser of a half- 

 shadow polarimeler. Under these circumstances the plane of 

 polarisation of the light, after its passage through the tube, passes 

 in succession through all the positions between two limits, one 

 of which corres(wmds to the maximum current in one direction, 

 ami the other to the maximum current in the opposite direction. 



