122 



NATURE 



, {Dec. 4, 1879 



To test the question as to whether the vortex of air about the 

 mirror had any effect on the deflection, the speed was lowered 

 to 192, 128, 96, and 64 turns per second. If the vortex had any 

 effect, it should have decreased with the Lwer speed, but no such 

 effect could be detected. 



Finally, to test if there were any bias in making the observa- 

 tions, the readings in several sets were taken by another, and the 

 results written down without divulging them. The separate 

 readings, as will be shown in the following specimen, were as 

 consistent as when made by myself, and the final results agree 

 with those of other observations : — 



Specimen of Observations 

 June 17, Sunset. Image good (best in column 4). 

 (.) (2) (3) (4) (5) 



112-81 112S0 112-83 11274 11279 



112-81 H2 - 8t 112-81 11276 112-78 



11279 11278 11278 11274 11274 



H2 - 8o 11275 11274 11276 11274 



11279 H277 11274 11276 11277 



112-82 112-79 112-72 112-78 112-SI 



112-76 112-73 11276 112-78 11277 



112S3 11278 112-81 112-79 11275 



112-78 11279 112-74 112-83 112-82 



112-82 112-73 112-76 11278 112-82 



Means = 112-801 112-773 192769 112-772 112-779 

 Zero = 0-260 0-260 0-260 0260 0-260 



d — 112541 112-513 112-509 112-512 112-519 



Temp. = 77°, B = + 1-500, cor. = - 0-144, dift". = + 1-356, 

 added to 256-070 = 257-426 = n 

 28155 = r 

 Remits from the above. 



299,660 299,740 299,740 299,740 299,720 

 Data for Working out Observations 

 Ut 3 fork makes 256-070 vibr. per sec. at 65 F. 

 E> = 3,972-46 feet, 

 tan o = tangent of inclination of plane of rotation = 0'02. 

 c x = log = 0-51457. 

 c = log = 0-49670. 

 d — deflection as read from micrometer. 

 r = radius. 

 <p — angle of deflection. 

 n — number of revolutions per second. 

 V = velocity of light in kilometres. 



B = number of beats per second between electric Ut a fork 

 and standard Ut 3 fork. Electric fork makes 

 \ (256-07 + B + cor.) vibr. per second, and « is a 

 mnltiple submultiple or simple ratio of this. 

 Cor. = correction for temperature of standard, 

 = - 0'0I2 v.s. per degree F. 



Mean result 1 299,728 



Cor. for temp. +12 



Vel. of light in air 

 Cor. for vacuum 



Vel. of light in vacuo 



299,740 



299,828 kilometres per second. 



SCIENTIFIC SERIALS 

 American Journal of Science and Arts, November. — Mr. 

 Stockwell, who has been systematically examining the physical 

 theory of the moon's motion, here calls attention to a secular 

 inequality in that motion, produced by the oblateness of the 

 earth. For attracted points out of the plane of the equator, and 

 not beyond the parallels of 35° 16' (which is the moon's case), 

 the attraction of the earth is less than it would be if the latter 

 were spherical. The author says he has found several ine- 

 qualities in the moon's motion, not recognised by existing 

 theories, and of even greater practical importance than the fore- 

 going. — The diamagnetic constants of bismuth and calc-spar in 

 absolute measure have been determined by Prof. Rowland and 

 Mr. Jacques. In their paper the former develops mathematical 

 expre^sions for the various coefficients of magnetisation, while 

 the latter describes the experimental method adopted : first, 

 exploration of the field, and then noting the time of swing of 

 1 In the original a table of observations appears which we are obliged to 

 rnit for want of space, while we give the result of the same. 



little suspended bars of the substances in it. The constants for 

 bismuth are 



l £, = - -000000012554 ) 



I k„ = — -000000014324 \ ' 

 for calc-spar, 



j ^i = - -000000037930 ) 



I £ 2 = - -000000040330 ( ' 

 — Mr. Gibbs's elaborate paper on vapour-densities is here con- 

 cluded. The relation between temperature, pressure, and volume 

 for the vapours of peroxide of nitrogen, formic acid, acetic acid, 

 and perchloride of phosphorus, differs widely from that expressed 

 by the usual laws, and the hypothesis of a compound nature of 

 the vapour is probable. Mr. Gibbs had proposed equations to 

 express the relations between temperature, pressure, or volume, 

 and quantities of the components in such a "gas mixture of con- 

 vertible components." In his paper he reviews all known experi- 

 mental determinations of the vapour densities, and finds fair 

 agreement with formula. — We note also accounts of Mr. 

 Michelson's recent experimental determination of the velocity of 

 light ; of the remarkable Kane Geyser well (arising from a con- 

 flict between gas and water in a petroleum region), and of Mr. 

 Edison's resonant tuning-fork. — Besides Prof. Marsh's recent 

 address, there are further notes by him of new Jurassic mammals 

 from the Rocky Mountains, showing a resemblance to known 

 types of the Purbeck in England. 



The American Naturalist, vol. xiii. No. II, November, con- 

 tains : — B. B. Redding, How our ancestors in the Stone Age 

 made their implements ; Isaac C. Martindale, Colorado plants-; 

 C. G. Siewers, Mould as an insect destroyer ; \V. N. Lockington, 

 Notes on Pacific Coast fishes and fisheries ; William Trelease, On 

 the fertilisation of our native species of ClitoriaandCentrosema ; 

 Recent Literature ; General Notes ; Scientific News ; Proceed- 

 ings of Scientific Societies. 



Annalcn dcr Physik und Chemie, No. 10. — A useful paper by 

 Ilerr Fromme, in this number, treats of the electromotive force 

 of the Grove, Bunsen, and Daniell batteries, as related to concen - 

 tration of the liquids. The force of a Grove, whenever this cell is 

 traversed by a very weak current, decreases continuously with con- 

 centration of nitric acid and approximately in proportion. That 

 of the Bunsen, under like conditions, is, for the higher concentra- 

 tions, about equal to that of the Grove, but from a concentration 

 C = 55 greater, because it remains constant, while the decrease 

 in the Grove goes on. The force of the Grove increases with 

 increased concentration of the sulphuric acid to a maximum 

 between C = 25, and C = 35, and thereafter decreases at a 

 more rapid rate. — HerrKundt and Heir Kontgen have succeeded 

 in proving electromagnetic rotation of the plane of polarisatron 

 in several of the less easily condensed gases ; and quantitative 

 results for air, hydrogen, oxygen, carbonic oxide, and marsh gas, 

 are here given. The rotation is in direction of the positive 

 current (as with water and sulphide of carbon), and its amount is 

 approximately proportional to the density. It is estimated that 

 253 km. air in the north-south direction would give a rotation of 

 1°. The author's apparatus (including a means of compression to 

 about 250 atm.) is described. — Prof. Lommel contributes two 

 papers ; in one of them, on Newton's dust rings, he seeks to 

 show the adequacy of the diffraction-theory to explain the pheno- 

 mena, as against the diffusion theory (interference of diffusely 

 reflected light) ; in the other paper, on Stokes's law, he contro- 

 verts M. Lamansky's experimental support of the general validity 

 of this law, which he (Prof. Lommel) had before impugned, as 

 inapplicable to a certain "critical region" in which the fluor- 

 escence and ab orption-spectra overlap. — Herr Wiillner describes 

 a five-band spectrum of oxygen obtained both from the positive 

 and the negative light in spectral tubes, to which was admitted 

 oxygen produced by electrolysis. When the charge of gas was 

 allowed to stand a quarter to half an hour, the spectrum was 

 changed into that of carbon, — Herr Narr endeavours further to 

 show that the loss of electricity by an insulated body in a gas 

 cannot alone be explained by rise of temperature of the gas, or 

 conduction through the insulating supports, or the presence of 

 particles of foreign substances, as dust, water, or mercury 

 vapour. Nor is there, apparently, a special conductivity of the 

 gas in the ordinary sense. — The changes of density produced in 

 steel by hardening and annealing, are indicated by Herr Fromme. 

 — Herr Riecke has a mathematical paper on the doctrine of the 

 poles of a bar-magnet ; and Herr Gerland shows historical 

 reason for believing that the caloric engine was conceived by 

 Leibnitz in 1706, and that Papin is alone the inventor of the 

 centrifugal pump. 



