Feb. 24, 1 881] 



NA TURE 



\o-. 



"On a Methid of Destroying the EtTects of Slight Errors of 

 Adjustment in Experiments of Changes of Refrangibility due to 

 Relative Mo'ions in the Line of Sight," by E. J. Stone, F.R.S., 

 Director of tlie Rndcliffe Observatory, Oxford. 



Let arrangements be made for the reversion of the prisms 

 without any disturbance of tlie other optical arrangements, in- 

 cluding, of course, the position of the cylindrical len<, if one be 

 used. Any slight errors of adjustment which prevent the light 

 from the star and the comparison light from falling upon the 

 train of prisms under the same optical circumstances, so far as 

 mere directi m is cmcerned, will have opposite effects in the re- 

 versed positions of the prisms ; but the separation of the emergent 

 lights due to relative motion will remain unchanged by the 

 reversal of the positions of the prisins. 



If, theref jre, the apparent change of refrangibility due to 

 relative motion remains unchanged by the reversion of the 

 prisms, all doubts about the effects of errors of adjustment will 

 be removed. But if the results in the reversed positiins of the 

 prisms sensibly differ, then the existing errors of adjustment 

 must be removed, or their effects allowed for by taking a mean 

 of the results in reversed positions, before any reliance can be 

 fairly placed upon the determination of relative motions in the 

 line of sight. 



A reversible spectroscope was arranged by me, and made by 

 Mr. Simms, some yeirs ago, but I have never since had an 

 equatorial, with a good driving clock, under my control, with 

 which the experiment indicated could be properly tried. 



With the direct prisms now iu use the required reversion can 

 be easily arranged. I am not likely for some time to have the 

 use of a good equatorial, and I therefore publish the plan with 

 the hope that some one more fortunately situated may give it a 

 fiir trial. 



The experiment is a crucial one, and in my opinion should be 

 tried. 



Chemical Society, February 3. — Dr. Gladstone, vice-pre- 

 sident, in the chair. — It was announced that a ballot for the 

 election of Fellows would take place at the next meeting of the 

 Society. — Th; following papers were read: — On the estimation 

 of organic carbon in air, by Drs. Dupre and Hake. The carbon 

 ii converted into carbonic acid by passing the air over heated 

 oxide of copper ; the carbonic acid thus produced is absorbed by 

 baryta water, and the carbonate is converted into sulphate which 

 is weighed. The carbonic acid present in the air, as such, in 

 estimated in a similar way and deducted. The mean quantity of 

 organic carbon in ten litres of ordinary London air was o-oooi54 ; 

 Boussingault and Verser found ten times as much. The authors 

 also refer to the results obtained by Pettenkofer in his well- 

 known experi:nents on the elimination by animals of H and 

 CH4. Pettenkofer seems to hive entirely neglected the organic 

 carbon in the atmosphere, and thus his results require very 

 important corrections.— On jthe action of the copper-zinc couple 

 upon nitrates and the estimation of nitric acid in water analysis, 

 by M. W. Williams. Some strips of clean zinc foil are placed 

 in a wide month stoppered bottle and covered with a 3 percent, 

 solution of copper sulphate : when the zinc has acquired a suffi- 

 cient coating of copper the solution is poured off and the copper 

 zinc couple washed. The water to be analysed is then poured 

 on the couple and allowed to remain for some hours at 24° C, 

 after the addition of a little pure sodium chloride. The nitrates 

 are thus completely converted into amm mia, which is estimated 

 by nesslerising. — On the position taken by the nitro-group on 

 nitrating the dibromo-toluenes, by R. Nevile and A. Winther.— ■ 

 On some of the various derivatives of toluene and the tolnidines, 

 by R.' Nevile and A. Winther. 



Anthropological Institute, January 25. — Anniversary 

 Meeting. — Edward B. Tylor, F.R.S., president, in the chair. — 

 Dr. Tylor, the retiring president, gave the annual address on 

 the year's progress of the science of man and civilisation. He 

 described the excellent arrangements in the United States for 

 supplying Indian agents, missionaries, and others in contact with 

 native tribes, with manuals to guide them in collecting informa- 

 tion as to laws, customs, languages, religion, (Sic, the very 

 memory of which will die out with the present generation of 

 Indians. He contrasted the .active intelligence of the United 

 States in this with the fact that the Dominion of Canada, though 

 kindly and wise in their practical management of the Indians, 

 do not seem alive to the v.ilue of the scientific knowledge which 

 is being lost among them for want of a little cost and trouble in 

 collecting it. Dr. Tylor also spoke of Prof. Flower's study of 

 the mountaineers of Fiji, the Kai Colo, a race who have the 



narrowest skulls of all mankind. The public have not yet 

 become aware of the value of minute measurement of skull 

 dimensions, but Prof. Flower has clearly shown in it a means of 

 bringing the study of races under arithmetical calculation, a step 

 which will do much to bring anthropology among the exact 

 sciences. — The new president is Majnr-General A. Pitt-Rivers, 

 F.R.S. 



Physical Society, February 12. — Prof. W. G. Adams in 

 the chair. — This being the annual general meeting, the yearly 

 report was read by the Chairman. The report showed that the 

 Society now numbered 321 members as against 298 of last year. 

 Two eminent members. Sir T. H. Elliot and the Rev. Arthur 

 Rigg, had been lost by death. The Society had decided to 

 republish the scientific papers of Dr. Joule in a collected form. 

 — Dr. Atkinson, treasurer, read the balance-sheet for the past 

 year, which showed the Society to be flourishing. — The new 

 Council and Officers were then elected. Sir W. Thomson retain- 

 ing the presidency. — Mr. Bakewell and Herr G. Wiedemann 

 vpere created Honorai7 Members. — Votes of thanks were passed 

 to the Lords Commissioners of the Council of Education for 

 granting the u'e of the meeting-room to the -Society, to Prof. 

 Adams and to Dr. Guthrie, the demonstrator, the auditors, and 

 the secretaries. Professors Rheinhold and Roberts. — The meeting 

 was then resolved into a special general meeting, and a resolution 

 put and carried giving the Council power to invest money of the 

 Society in the name of the Society, or of persons appointed by 

 them, in certain stock, home and foreign. — The meeting was 

 then constituted an ordinary one, and Mr. T. Wright on, C.E., 

 read a paper by Prof. Chandler Roberts and hi nself on the 

 density of fluid bismuth. By means of the oncosimeter, an 

 in.strument which records on a band of paper the sinking or 

 floating effect of a ball of the solid metal immersed in the 

 molten metal, they had determined the density of fluid bismuth 

 from six experiments 1 1 be lo'o55. A former value by a dif- 

 ferent method was io"039. In the discussion which en ued, 

 Mr. Wrightson stated that his experiments proved solid cast 

 iron to be heavier than fluid, and to sink in the latter when first 

 immersed, but it rapidly became lighter as its temperature rose, 

 till it floated v\hen in its plastic state, and was consequently 

 lighter than when in the molten state. The oncosimeter could 

 be utilised for determining the change of volume in melting 

 rocks, and Prof. Chandler Roberts suggested that it might throw 

 light on the difference of state between the carbon of grey pig 

 and white iron. — Dr. O. J. Lodge exhibited working models 

 showing the hydnstatic analogies between water and electricity. 

 A battery was represented by a pump, conductors byojjen pipes, 

 dielectrics by a pipe closed by an elastic membrane, electrome- 

 ters by pressure ganges. With these analogues he showed the 

 action of a Leyden jar, and the passage of telegraphic signals 

 along a cable. 



Geological Society, February 2. — Robert Etheridge, F.R.S., 

 president, in the chair. — Joseph Groves, George Lewis, Rev. 

 Edouard Mechin. S.J., James Osborne, and the Rev. William 

 Sharman were elected Fellows of the Society. — The following 

 comiiunications were read : — On the coralliferous series of Sind 

 and its connection with the last upheaval of the Himalayas, by 

 Prof. P. Martin Duncan, F.R.S. — This communication is the 

 result of the author's study and description of the fossil corals 

 of Sind, und -rtaken at the request of the Geological Survey of 

 India. The history of the researches in the geology of the 

 Tertiary deposits of Western Sind was noi iced in relation to a 

 statement made so ne years since by the author and Mr. II, M. Jen- 

 kins, F.G.S., that there vi-as more than one Tertiary series there, 

 in opposition to both D'Archiac and Haime. After a brief 

 description of the geology of the Khirthar and Laki ranges of 

 hills, which were called Hala Mountain by the French geolo- 

 gists', the succession of the stratigraphical series demonstrated 

 by the survey under Blanford and Fedden was given, and the 

 author proceeded to discuss the peculiarities of the six coral 

 faunas of the area, and to argue upon the conditions which pre- 

 vailed during their existence. A transitional fauna, neither 

 Cretaceous nor Eocene, underlies a trap; to the trap suceeds a 

 Teat development of Nummulitic beds containing corals, the 

 Ranikot series, some of which are gigantic representatives of 

 European Nummulitic forms. A third fauna, the Khirthar, 

 succeeds, and a fourth, Khirthar Nari, which was a reef-building 

 one ; and a fifth, the Nari, is included in the Oligocene age. 

 An important Miocene coraUiferous series (the Gaj) is on the 

 top of all. These faunas above the trap are Nummulitic, Oligo- 

 cene, and' Miocene in age, and in the first two European forrns 



