3o6 



NATURE 



IJan. 30, 1879 



Royal Academical Institution, Belfast. In 1872 he became a 

 student at Queen's College, Belfast, where he succeeded in 

 winning several scholarships and also two Peel Exhibitions, one 

 for general proficiency and the second for mathematics. In 

 1875 he was elected to an open scholarship at St. Peter's, and in 

 October of that year he graduated B.A. at the Queen's 

 University, subsequently proceeding M.A. On each occasion he 

 obtained a first-class for mathematical science, and was awarded 

 a gold medal. He has won several college prizes during his 

 residence at Cambridge. Mr. Walker is a native of Durham, 

 and was educated at Durham University, of which he is a 

 Fellow, and proceeded to Queen's College in October, 1875. 

 He has been a prizeman of the college for mathematics. Mr. 

 Pearson was educated at University College School, and also 

 under private tuition with the Rev. L. Hensley, of Hitchin. He 

 gained an open scholarship at King's College in 1875, and has 

 been each year college prizeman in mathematics. 



A Report just published by the Swiss Statistical Board gives 

 some information as to the state of primary instruction in the 

 various cantons of Switzerland. Out of 21,875 recruits examined 

 during the year 1S77, 11 '7 percent, proved to have primary in- 

 struction quite insufficient, and were sent back to the primary 

 military schools. The better educated cantons are those in which 

 manufactures are more developed, namely, Basel (town), Geneva, 

 and Zurich, S chaff hausen and Thurgau. The worst educated are 

 those of Appenzell (land), Uri, Wallis, and Freiburg (Catholic). 

 Primary education seems to have become worse during recent 

 years, as the results for 1877 are far below those of 1876. 



SCIENTIFIC SERIALS 



Journal of the Franklin Institute, December, 1878. — From 

 experiments here described by Mr. Jacques, it appears that cur- 

 rents of air of varying density, as in Tyndall's well-known experi- 

 ment, not only diminish the intensity of a sound, but affect its 

 distinctness. This holds good especially for the human voice, 

 and for musical instmments with few overtones (as the flute). 

 The effect on the voice is that of a repetition of each syllable 

 several times in close succession. Sound-waves were traced out 

 in the space of an auditorium in Boston, and their confusion 

 shown on introducing air currents. The good acoustic properties 

 of the Baltimore Academy of Music are proved to be due to 

 arrangements by which a large volume of air is conducted, in 

 gentle current, across the stage and diagonally towards the roof. 

 When, by closing certain valves, ventilation was arrested and 

 currents of circulation generated, the sound was noticed to be 

 "dead," or " confused and indistinct." — Dr. Dudley investigates 

 the chemical composition and physical properties of steel rails, 

 deducing some rules for guidance of the Pennsylvania Railroad 

 Company. — Mr. Dupuy writes on the direct process of making 

 wrought iron and steel, — Mr. Dumont on tests of boiler i^-on, — 

 and Prof. Haupt on the use of the heliotrope in geodetic surveys. 



The Archives des Sciences physiques et naturelles (parts 251 

 and 252, November and December) contain the following papers 

 of interest : — On ytterbina, a new earth contained in gadolinite, 

 by C. Marignac. — On a transformation of dibromethylene into 

 an acetone with four atoms of carbon, brought about by the 

 action of hypobromous acid, by E. Demole. — A note on Dr. 

 Heine's work on the formation of mountains, by E. Renevier. — 

 On the geography and archaeology of forests, by Dr. Asa Gray. 

 — Recent researches in solar chemistry, by J. Norman Lockyer. 

 — Observation of a case of migration of carps, by A. Bar- 

 tholoni. — On a general method of continuous integration of any 

 numeric function, applied t® several theorems furnished by the 

 mathematical analysis of the calculation of the curves of a new 

 thermograph, by Raoul Pictet and Gustave Cellerier. — On the 

 limnograph of Secheron, near Geneva, by Ph. Plantamoiu". — A 

 note on the useful effect of magneto-electric machines and the 

 production of elecb-ic light, by A. Achard. — On the reappearance 

 of Encke's comet of short period, with a history'^f this comet, by 

 Alfred Gautier. — Some remarks on the migration of carps by G. 

 Lunel. — On the ophite of Spain, by M. Calderon. 



Bulletin de r Academie Royale de Belgique, Ncs. 9 and 10, 1878. 

 — This contains an account, by M. Dupont, of a recent important 

 ' ' find " of fossils in the Sainta Barbe, one of the coal mines of 

 Bemissart (a village near the French frontier), consisting of five 

 skeletons of large adult iguanodons together with tortoise-, 

 numerous fishes, and plant-impressions, constituting a fauna and 

 flora wholly new for the country. The bones are unfortunately 



impregnated with pyrites, so that they are readily disaggregated 

 on contact with air, but they have been carefully removed in 

 plaster to Brussels, after precise noting of position, &c. The 

 fossils were found at se\eral different levels separated by layers 

 of sterile clay. There i- no indication of molluscs of any kind. 

 The deposit is thought to be of the Wealdian horizon, and is 

 remarkable, both in itself, and in its relations to the subterranean 

 r graphy of the valley of Mons, and the lower cretaceous strata 

 of Hainaut. — M. Plateau writes on a law of the persistence of 

 impressions in the eye. With two disc having the same number 

 of sectors, and the white sectors <.i the one being equal in 

 angular width to the black discs of the other, the " times of 

 apparent constancy," of the two im ressions are to each other 

 in inverse ratio of the brightnesses of the two grey tints produc- 

 ing these impressions. A complete impression, whether intense 

 or weak, has no appreciable time of apparent constancy ; and 

 the time is longer, the more incomplete the impression. The 

 degree of illumination of the object has but a weak and indirect 

 influence on the time of apparent constancy. — M. Longchamps 

 contributes further additions to the synopsis of the Gomphines ; 

 and M. Kenard lithological researches on the phtanites of the 

 carboniferous limestone of Belgium. — M. Montigny describes 

 an experimental arrangement for the study of coloured stars. 



SOCIETIES AND ACADEMIES 

 London 



Royal Society, December 19, 1S78. — " On the Torsional 

 Strain which remains in a (ilass Fibre after Release from 

 Twisting Stress," by J. Hopkinson, D.Sc, F.R.S. 



It has long been known that if a wire of metal or fibre of 

 glass be for a time twisted, and be then released, it will not at 

 once return to its initial position, but will exhibit a gradually 

 decreasing torsion in the direction of the impressed twist. The 

 best method of approximating to an expression of the facts has 

 been given by Boltzmann (" Akad. der Wissensch. zu Wien," 

 1874). He rests his theory upon the assumption that a stress 

 acting for a short time will leave after it has ceased a strain 

 which decreases in amount as time elapses, and that the prin- 

 ciple of superposition is applicable to these strains, that is to- 

 say, that we may add the after-effects of stresses, whether simul- 

 taneous or successive. Boltzmann also finds tha% if <p (/) t be 

 the strain at time t resulting from a twist lasting a very short 



A 



timer, at time t = o,tp{t) = _, where A is constant for mode- 

 rate values of t, but decreases when t is very large or very small. 



The glass fibre I examined was about t\^enty inches in 

 length. The glass from which it was drawn was composed of 

 silica, soda, and lime ; in fact, was glass No. i of my paper on 

 "Residual Change of the Leyden Jar" {Fhil. Trans., iSyj). 

 In all cases the twist given was one complete revolution. The 

 deflection at any time was determined by the position on a scale 

 of the image of a wire before a lamp, formed by reflection from 

 a light concave mirror, as in Sir W. Thomson's galvanometers 

 and quadrant electrometer. 



The first point to be ascertained from the results was 

 whether or not the principle of superposition, assumed by 

 Boltzmann, holds for torsions of the magnitude used. 



The experiments indicate a large deviation from the principle 

 of superposition, the actual effect being less than the sum of the 

 separate effects of the periods of stress into which the actual 

 period may be broken up. 



A 



They also appear to indicate the form ((>(t) = — , o being less 



than, but near to, unity. If a = 0*95 we have a fairly satis- 

 factory formula for the case in which the fibre was twisted two 

 hours. 



In the author's paper on "Residual Change of the Leyden 

 Jar " that subject is discussed in the same manner as Boltzmann 

 discusses the after-effect of torsion on a fibre, and it is worth 

 remarking that those results can be roughly expressed by a 



formula in which <p (t) = 



For glass No. 5 (soft crown) 



o = 0'65, whilst for No. 7 (light flint; it is greater : but in the 

 electrical experiment no sign of a definite deviation from the law 

 of superposition was detected. 



January 16. — " On the Effect of Strong Induction-Currents 

 upon the Structure of the Spinal Cord," by William Miller Ord, 

 M.D. 



