48o 



NA TURE 



[March i8, 1886 



cubic expansion (vaiiation of density with temperature), the two 

 last being easily determined even with small samples by means 

 of the fluid of iodides uh-eady recommended by him. — Remarks 

 on M. Mushketoff's orographic and geological description of 

 Turkestan, by M. Daubree. Of the three volumes of explana- 

 tory text to the map of Russian Turkestan (scale I : 1,250,000), 

 the first has now appeared. It contains a summary of the 

 explorations of Turkestan from the remotest times down to the 

 year 1884, and a geological description of the Aralo-Caspian 

 steppes, with a small geological map of Turkestan. 



Berlin 



Physical Society, January 22. — Dr. Konig spoke of some 

 photometers he had quite recently tested in respect of their 

 precision. The simple Bunsen photometer, consisting of a 

 screen of fine writing-paper smeared with a grease spot, laboured 

 under the drawback that it was not possible to contemplate 

 simultaneously the two sides it was desired to compare. 'I'here 

 were several modifications of this apparatus planned with a view 

 to overcoming this defect. First, there was the application of 

 two mirrors inclined at 45°, by means of which both surfaces 

 were seen in juxtaposition. Other contrivances for the same 

 purpose were the application of a prism, tlie edge of which lay 

 in the plane of the screen, the use of two prisms, and, further, the 

 use of two totally reflecting piisms with lenses. The last-named 

 description of photometer, as also the mirror-photometer, were 

 very exact, but it now appeared that it was not possible to cause 

 the spot of grease wholly to vanish from view. For such precise 

 photometers there would, on the contrary, have to be found two 

 substances which reflected and transmitted the light differently, 

 but yet absorbed it with equal strength and possessed the same 

 structure. Weber s photometer was constructed according to 

 an entirely different principle. It consisted in the main of a 

 small benzene lamp, wliich was placed in a tube in front of a 

 mirror and which ilhunined a milk-glass plate displaceable in the 

 tube. From the illumined milk-glass the light was carried to a 

 totally reflecting prism, and thence into the eye-piece, where it 

 lighted up the half of the field of vision. The other half received 

 light from a milk-glass plate standing in the direction of the 

 eye-piece behind the prism. This milk-glass plate was illumined 

 by the light which was to be measured. In the case of like- 

 coloured light the registrations of the Weber photometer were 

 very exact, but in the case of different-coloured lights such pre- 

 cision was not obtained. Of the means employed by Herr Weber 

 to measure different-coloured lights with his photometer, tliat 

 which consisted in bringing first a red, then a green, and there- 

 after a blue glass before the eye-piece, and taking the average of 

 the three measurements, was still at this day the most approxim- 

 ately exact, but was yet inadequate. A great advantage belong- 

 ing to the Weber photometer, on the other hand, was that by 

 means of it the scattered daylight could be measured. The 

 readily available Weber photometer woidd prove itself particu- 

 larly useful for the purpose of testing the conditions of illumina- 

 tion in school-rooms. — Dr. Grunmach reported on the baro- 

 metric investigations carried out by him in the Normal Gauging 

 Oftice. He described at length the arrangement of the normal 

 barometer, the vacuum of which was measured in an electrical 

 way. A combination of the barometer-vacuum with a Geis>.ler 

 tube permitted the attenuation to be examined even beyond the 

 limits of the pressures measurable by the cathetometer. The 

 occurrence of the phosphorescence light in the spectral tube was 

 a standard for the highest degrees of attenuation, in which the 

 vacuum was filled with quicksilver vapour of the tension of only 

 o'oi to o'02. A still better vacuum would be achieved when 

 the quicksilver vapour was made to be absorbed, a condition 

 which the speaker had in vain tried to effect with selen- 

 ium. With this barometer was compared a large number of 

 normal barometers according to a method described at large by 

 the speaker, and with the application of the developed formulse 

 of reduction. Under these comparisons it appeared that the 

 impurity of the free quicksilver-cup heightened the meniscus, and 

 thereby the registrations also of the barometer. In the case of 

 older barometers, a series of other disturbing influences like- 

 wise showed themselves, which would have to be further inves- 

 tigated. In the discussion which followed this address. Dr. 

 Goldstein proposed for the electrical measurement of the 

 vacuum, instead of Geissler's spectral tube, the employment of 

 a wide tube which let the fluorescence light pass more obviously 

 into the phenomenon ; and/or the graduations of these highest 

 degrees of attenuation the thermometer would, he maintained 



be better adapted than were the optical phenomena. Let, 

 namely, a thermometer be brought into a vacuum-tube whose 

 positive pole was a point, but whose negative electrode was a 

 steel plate nearly filling out the tube in Iront of the cathode : 

 then the thermometer, when the attenuation reached such a 

 degree that the cathode light appeared would mount 80° to 90° 

 above the temperature of the room. At the positive pole the 

 thermometer rose only about 3°. This rise of temperature in 

 the cathode light occurred in connection with the degree of 

 attenuation, and might be utilised for the measurement of these 

 degrees. 



BOOKS AND PAMPHLETS RECEIVED 



Books ; — " Schriften der Naturforschenden Gesellsctiaft in Danzig," Neue 

 Folge, Sechsten Eandes, Drities Heft (Danzig). — " The Construction of 

 Harbours," 3rd edition, by 'Ihos. Stevenson (A. and C. Black). — "Three 

 Years of Arctic Service," 2 vols., by A. W. Greeiy (Bentley).— " The 

 Quarterly Journal of Microscopical Science," February (Cliurchill). — " Fac- 

 tional Electricity," by T. P. Treglohan (Longmans). — "Hand-Book of the 

 History of Philosophy," by E. Belfort Bax (Bell).— "Treatise on Si.itics," 

 vol. ii., 3rd edition, by J. M. M.nchin (Clarendon Press). — "Analisi delle 

 Ipotesi Fisiche," by C. Zauon (londelli, Venice).— " Proceedings of the 

 .'American .\cademy of Arts and Sciences." May to October 1885 (Wilson, 

 Boston). — '* Transactions of the Anthropological Society of Washington," 

 vol. iii. — " Proceedings of the Academy of Natural Sciences of Philadelphia," 

 part 3 (.August to December 1885). — Memoirs of the Geological Survey of 

 India : " Palieontologia Indica," ser. x. ; " Indian Tertiary and Post-Tertiary 

 Vertebrata," vol. iii. parts 7 and S; " Siwalik Crocodilia, Lacertilia, and 

 Ophidia, and Tertiary Fishes," by R. Lydekker (Triibner). — " Hong Kong 

 tJbservatory Reports," May to November 1885. — Pamphlets: — "On 

 the Movement Cure in China," by D. J. Macgowan. — " The Present Posi- 

 tion of the Museum and Art Galleries of Glasgow, 1886" (Anderson, Glas- 

 gow). — " Twenty-ninth Annual Report on Free Public Libraries and Aluseum 

 of Sheffield." — " Les CranesditsDeformcs,"by J. Ignaciode Armes (Havana). 

 — " Cellulose." by C. F. Cross and E. J. Bevan(G. Kenning).— "Separatab- 

 drack MIS dem Repertoriiim der Physik,"by Dr. F. Exner.—" The Typhoons 

 of the C inese Seas in the Year 1885 ; Essay on the Atmospheric Variations 

 ill the Far East during January 18S5," by R. P. Marc Dechevrens (Kelly 

 and Walsh, Shanghai). 



CONTENTS p.u;e 



A TextBook of Political Economy. Jjy Prof. R. 



Adamson 457 



Algae 45b 



Our Book Shelf :— 



Ripper's " Practical Chcraislry, with Notes and Ques- 

 tions on Theoretical Chemistry " 459 



Greenwood's "Free Public Libraries.'' — W. Odell 459 



Giilleau's " Aerostats dirigeables " 460 



Letters to the Editor : — 



Clifford's "Mathematical Fragments." — R. Tucker 460 

 The Upper Wind Currents in the South Indian Ocean 

 and over the N.W. Monsoon. — Hon. Ralph 



Abercromby 460 



Glacier Bay in Alaska.— G. W. Lamplugh ... 461 

 A Correction, and the Distribution of Appendicularia. 



— Prof. W. A. Herdman 461 



Motley's "Ortjanic Chemistry "—Correction. — Dr. 



F. K. Japp,'^K.R.S 461 



"Peculiar Ice-Forms."— B. Woodd Smith ... 461 

 Remarkable Discovery of Rare Metals in Diluvial 



Clays 461 



Harvard College Museum Report 462 



Technical Education in New South 'Wales .... 462 



Seebohm's History of British Birds . 463 



Notes , 464 



Our Astronomical Column : — 



Dark Transits of Jupiter's Fourth SateUite .... 466 



Nova Andromedas of 1885, and Nova Scorpii of i860 466 



Fabry's Comet 466 



Barnard's Comet 466 



Astronomical Phenomena for the Week 1886 



March 21-27 466 



Biological Notes ; — 



The Pelagic Stages of Young Fishes 467 



Danais archippus — an Enterprising Butterfly .... 467 



Geograpnical Notes 4^7 



The Sun and Stars, III. Hy J. Norman Lockyer, 



F.R.S. (Illiistraled) 4^9 



Univeraity and Educational Intelligence 472 



Scientific Serials 472 



Societies and Academies . 47j 



Books and Pamphlets Received 480 



