6i6 



NA TURE 



[October i8, iqcxj 



bright, owing probably to the transmission of some red rays by 

 the cobalt glass, but the addition of a film stained with Prussian 

 blue, by which these rays are absorbed, greatly improves the 

 red. On the other hand, a pale yellow film which cuts off the 

 violet causes ihe violet of the spectrum on the blue ground to 

 stand out brightly, while a purple film brings out the green, 

 which, owing to the green light transmitted by ordinary cobalt 

 glass, is generally a good deal enfeebled. In each case the con- 

 trast of the two spectra seen by different eyes is so well marked 

 that the experiment seems likely to be of service in teaching. 



The complementary colour to red is shown to consist, not of 

 one simple colour-sensation, but of two at least, namely, green and 

 riolet, and in the author's case of blue also. Against a magenta 

 'background the complementary colour is seen to be spectral 

 green. But in this case the physical stimulus is complex. On 

 adding to the magenta a yellow glass, to cut out the violet, or 

 using candle light, the violet reappears in the complementary 

 spectrum, while if a blue glass is added instead, the violet 

 vanishes, and red stands out brightly in the spectrum. It may 

 be thus shown that the colour which has green for its comple- 

 raen'ary is not spectroscopically simple, and since the spectral 

 elemtnts of it have each a different and independent eflect upon 

 the spectrum of the complementary colour, the author concludes 

 that the green sensation has no special connection with the red, 

 ■or indeed with any single colour sensation. 



Manchester. 



Literary and Philosophical Society, October 2. — Prof. 

 Horace Lamb, F. R. S. (President), in the chair. — Mr. Thomas 

 Thorp described a method of producing a spectrum-like band 

 from a volumetric curve by the use of a photographic camera 

 with a cylindrical lens, and also gave a brief account of the solar 

 eclipse of May last as seen in Algiers. — A paper on plumbism in 

 pottery workers was given by Mr. William Burton, who dealt 

 with the subject from the technical point of view, showing how 

 the plumbism was caused by the inhalation or swallowing of 

 dust containing soluble lead compounds. It was pointed out 

 that the abolition of lead from the glaze was not a practicable 

 remedy, as leadless glazes suited to the conditions of the general 

 run of English pottery are not yet within the reach of the 

 manufacturers. Further, the abolition of lead from the glaze 

 would not affect those cases which arise from the use of enamel 

 or on glaze colour used in the form of dust or of spray, and no 

 one has yet ventured to suggest that the use of lead fluxes for 

 this purpose could be abolished. The existing remedies in the 

 shape of mechanical means for dealing with the dust in such a 

 way that it should neither be swallowed nor inhaled, the periodic 

 medical examination of the workers, and the proposed further 

 safeguards of converting all the lead used into compounds of 

 considerably lower solubility than those now employed, were 

 also treated of. The final opinion of the author was that the 

 combination of all these safeguards would, within a reasonable 

 time, render the operations of glazing and decorating pottery 

 with substances containing lead compounds as free from risk to 

 the operative as it was possible for any industrial occupation 

 to be. 



Paris. 



Academy of Sciences, October 8. — M. Maurice Levy in 

 the chair. — Note on the thirteenth conference of the Inter- 

 national Geodetic Association, by M. Bouquet de la Grye. 

 From the reports to the conference it appears that the whole of 

 Europe and North America will be shortly completely covered 

 by a network of triangles. Special observations have been 

 carried out under the direction of the central office in several 

 observatories to determine exactly the line of displacement of 

 the poles. An arc of meridian is being measured in Spitsbergen 

 by Swedish and Russian observers, and Great Britain has com- 

 menced the determination of an arc from the Cape to Alexandria, 

 which will join on to the European network through Asia Minor. — 

 Remarks by M. Guyon on the Connaissance desTemps for 1903. — 

 Observations of the sun made at the Observatoryof Lyons with the 

 Brunner equatorial during the second quarter of 1900, by M. J. 

 Guillaume. The results are summarised in three tables show- 

 ing the number of sunspots, their distribution in latitude and 

 ■the distribution of the faculse in latitude. — The total eclipse of 

 •the sun of May 28, 1900, observed at Elche (Spain), by M. 

 Lebeuf. The results of the observations on the times of 

 •contact are given. — Researches on the inverse effect of the 

 magnetic field which ought to produce movement in an electrified 

 ■body, by M. V. Cremieu. The application by Lippmann of the 

 principle of the conservation of energy to the experiments of 



NO. 1616, VOL. 62] 



Rowland on electric convection shows that, reciprocally, magnetic 

 variations ought to produce a movement of electrified bodies 

 placed in the field. The experiments carried out by the author, a 

 detailed description of which, with two diagrams, is given in the 

 paper, show that the expected effect is not produced. The 

 deflection upon the scale should according to the theory have been 

 of the order of 100 to 140 mm. No measurable deflection occurred. 

 Telegraphy without wires with relays. Inconvenience of the 

 Guarini relays, by MM. Guariniand Poncelet. — On iron silicide 

 SiFej, and on its presence in commercial ferrosilicons, by M. P. 

 Lebeau. A mixture of iron and copper silicide is heated for 

 several hours to the highest temperature of a wind furnace. The 

 mass is extracted with 10 per cent, nitric acid, when a crystalline 

 mass of iron silicide, FegSi, is left behind, which is further 

 purified by successive treatment with soda solution, nitric acid 

 and water. — On a new pyrogenous product from tartaric acid, 

 by M. L. J. Simon. An acid, CvHgOj, was obtained, differing 

 both in melting point and solubility from the acid of the same 

 composition previously obtained from the same source by MM. 

 Wislicenus and Stadnicki. Its potassium and silver salts were 

 prepared. — Acetyl derivatives of cellulose and oxycellulose, by 

 MM. Leo Vignon and F. Gerin. Cellulose acetylated by means 

 of acetic anhydride and zinc chloride gives a tetra-acetyl deriv- 

 ative ; oxycellulose behaves similarly, and the derivative thus 

 obtained clearly retains its aldehydic functions. — The Albien 

 and Cenomanian of Hainaut, by M. Jules Cornet, 



DIARY OF SOCIETIES. 



TUESDAY, October 23. 

 Royal Photographic Society, at 8.— A Demonstration of the Ozotype 

 Printing Process : Thomas Manly. 



FRIDAY, October 26. 

 Physical Society, at 5— Exhibition of Experiments illustrating certain 

 Phenomena of Vision : Dr. Shelford Bidwell, F.R.S.— On the Concentra- 

 tion at the Electrode in a Solution, with special reference to the Libera- 

 tion of Hydrogen by the Electrolysis of a Mixture of Copper Sulphate 

 and Sulphuric Acid : Dr. J. S. Sand.— Electromotive Force and Osmotic 

 Pressure ; Dr. R. A. Lehfeldr. 



SATURDAY, October 27. 

 Essex Field Club, at 6.30.— Contributions to the Pleistocene Geology of 

 the Thames Valley. The Grays Thurrock Area, Part I.: Martin A. C. 

 Hinton and A. S. Kennard. 



CONTENTS. PAGE 

 The Subordination of the Individual to the Wel- 

 fare of the Species. By E. B. P 593 



A Modern Text-Book of Optics . 595 



Agricultural Education in the United States. By 



Prof. R. Warington, F.K.S 597 



Our Bookshelf:— 



HoUeman : " Lehrbuch der Anorganischen Chemie." 



—A. S 598 



Linton : "Flora of Bournemouth, mcludmg the Isle 



cfPurbeck'' ... • • • • 598 



Weguelin : " Carnations and Picotees for Garden and 



Exhibition" 598 



Letteis to the Editor: — 



Collateral Heredity Measurements m Schools.— Prof. 



Karl Pearson, F.R.S . -599 



The White Rhinoceros on the Upper Nile.— Oldfield 



Thomas 599 



Disease of Birch Trees in Epping Forest and Else- 

 where.— Robt. Paulson .... . • . . 599 

 Sunspots and Frost^- Alex. B. MacDowall . 599 

 Simple Experiments on Phosphorescence.— A. M. M. 599 

 Mexican Symbolism. By Prof. Alfred C. Haddon, 



F.R.S 600 



Further Investigations on Xenia m Maize . . 601 



Portable Gas Producers. ^With Diagrams.) By 



Dr J. A. Purves 601 



Notes 602 



Our Astronomical Column : — 



Ephemeris for Observations of Eros 006 



New Planetary Nebula 606 



Paris Observatory, Annual Report . . . . ■ • • 606 

 Range-Finders. {Illustrated.) By Prof. W. Stroud 607 

 Mechanics at the British Association ••••_•• ^°9 

 Botany at the British Association. By A. C. S. . 610 

 University and Educational Intelligence. {Illus- 



trated.) 



614 



Societies and Academies 615 



Diary of Societies ^^^ 



