November 24, 1904] 



NA TURE 



to be eliminated in this way witiiin twenty-four hiours. 

 The amount of arsenic in the secretions of people in towns 

 where large metallurgical operations are carried on is found 

 in some cases to be as high as one-thirtieth of a grain per 

 gallon. 



A SECOND edition of Prof. Hantzsch's " Grundriss der 

 Stereochemie " has just been published by J. A. Barth in 

 I^eipzig. The rapid advances which have taken place in this 

 1:iranch of chemistry during the last ten years have rendered 

 considerable additicms necessary. Sections are now included 

 •dealing with the stereochemistry of diazo-compounds and 

 complex inorganic bodies, and with the molecular asym- 

 ■metry of nitrogen, sulphur, selenium, and tin compounds. 

 The connection between configuration and biological 

 activity, the reciprocal transformation of optical antipodes, 

 and the phenomenon of steric hindrance are also treated in 

 the new edition, which should be welcomed by all classes 

 ■of chemists. 



A THIRD edition of the " Elements of the Mathematical 

 Theory of Electricity and Magnetism," by Prof. J. J. 

 Thomson, F.R.S., has been published by the Cambridge 

 University Press. A new chapter on the properties of 

 moving electrified bodies has been added, and other minor 

 changes have been made. 



Messrs. Bell and Sons have published separately, under 

 the title " Examples in Algebra," a selection of the ex- 

 amples in the recently published " Elementary Algebra," 

 Tjy Messrs. W. M. Baker and A. A. Bourne. The price is 

 3^., and the new volume may also be had in two parts at 

 2'5. each. 



The yearly volume for 1904 of the Reliquary and Illus- 

 Irated Archaeologist has now been published. The four 

 separate issues, which have been referred to from time to 

 time in these columns, together form a handsome volume. 

 Some articles in the volume will appeal to students of science 

 ■who are not archjeologists. Among these may be mentioned 

 a well illustrated article by Mr. W. H. Legge " About 

 Almanacs," and Mr. F. W. Galpin's " Notes on a Roman 

 Hydraulus." 



In order to meet the requirements of the new syllabus in 

 chemistry of the matriculation examination of the University 

 of London, Dr. G. H. Bailey has taken advantage of the 

 demand for a second edition of his book on chemistry to re- 

 write and enlarge it. In its present form " The New 

 Matriculation Chemistry " contains everything that a 

 candidate at the matriculation examination is likely to re- 

 quire. An introductory course of experimental work has 

 been inserted in addition to other new matter. The volume 

 is published by Mr. W. B. Clive, and edited bv Dr. William 

 Brigq-s. 



OUR ASTRONOMICAL COLUMN. 

 Encke's Comet (1904 b). — On a photograph obtained on 

 October 28 with two hours' exposure, using the Bruce tele- 

 scope. Prof. Max Wolf discovered a faint image of Encke's 

 comet, the apparent position of which at 28d. yh. 13m. 48s. 

 <Konigstuhl M.T.) was 



a = 23h. 37m. 51 41S., 5 = -1-26° o' 38".o. 



A faint tail, extending in a northerly direction, was 

 suspected. 



On the same night Prof. Millosevich at Rome was able 

 to find the comet with the 30 cm. equatorial of the Roman 

 College Observatory. The object was extremely faint, and 

 had the following position at 6h. 30m. (October 28, Rome 

 M.T.I. a = 23h. 37m. 58s., 8 = -f-26° i'-4. 



Prof. E. Hartwig also observed the comet visually, using 

 the large refractor of the Bamberg Observatory, at 



NO 1830, VOL. 71] 



9h. i8m. IIS. (Bamberg M.T.) on October 30, and deter- 

 mined the following as its position : — 



a (app.) =23h. 28m. lois., 5 (app.) =-1-25° 23' 2s".i. 

 The comet was very diffuse with a faint central condensa- 

 tion, and a diameter of more than 10' {Astronomische 

 Nachrichtcn, No. 3977). 



Observations of Perseids. — The results of a large 

 number of independent observations of the Perseid. shower 

 of last August, together with a detailed exposition by M. 

 Chretien of the process by which the positions of meteor 

 radiants may be determined from the observed data by the 

 method of least squares, are published in the November 

 number of the Bulletin de la Societe astronomique de 

 France. 



.\mong other results, those obtained by M. Perrotin at 

 Nice and by M. G. A. Quignon at Mons are given. The 

 former have already been summarised in these columns ; the 

 latter are as follows : — 



During a total watch of 7h. 15m. between August 7 

 and 12, M. Quignon observed no meteors, chiefly Perseids, 

 and determined the position R..\.=44°, dec. =-1-59°, as 

 the mean radiant point of the shower. The maximum dis- 

 play took place between 22h. 40m. and 23h. lom. on 

 .August II, when 21 meteors, or 42 per hour, were seen. 



Heights of Meteors. — In a letter to the November / 

 number of the Observatory Mr. Denning publishes some 

 data regarding the observed heights of the appearances and 

 disappearances of several different classes of meteors. 



He states that, generally speaking, the swift meteors 

 become visible at a greater height than the slower ones, and 

 do not approach so near to the earth's surface before dis- 

 appearing. Thus for the Leonids and Perseids, both of 

 which are characterised by their comparative swiftness, it 

 has been determined that the former are generally more 

 lofty than the latter, the average heights being as follows : — 



Height at Height at No. of 



beginning ending meteors 



Leonids ... 84 miles ... 56 miles ... 25 



Perseids ... 80 „ ... 54 ,, ... 40 



On the other hand, the mean heights of the very slow 

 meteors appear to average about 65 miles at the beginning 

 to 38 miles at the end of their appearance. These, how- 

 ever, appear to form two distinct classes: — (i) those having 

 very low radiants, extending from 64 miles to 48 miles ; 

 and (2) those having fairly high radiants, extending from 

 66 miles to 28 miles. 



The swiftest meteors apparently become visible when 

 nearly 20 miles higher than the very slow meteors, whilst 

 those of the latter which have high radiants come 20 miles 

 nearer the earth than those having very low radiants. 



Seven Quadrantids and four Lyrids gave mean heights 

 of 67 miles to 52 miles and 84 miles to 50 miles respectively. 



The Photographic Spectrum of Jupiter. — Using the 

 large refractor of the Meudon Observatory in conjunction 

 with a spectrograph containing one 60" prism and having 

 a focal length of 292 mm., M. G. Millochau obtained a 

 number of photographs of the spectrum of Jupiter during 

 December and January. 



.\ study of the resulting spectra, which were obtained on 

 Lumi^re panchromatic plates and extend from F to C, 

 showed a number of bands at AA. 618, 607, 600, 578, and 

 515, which are apparently the same as those observed by 

 Keeler in the spectrum of Uranus. It further disclosed the 

 facts that the water vapour and a bands were greatly 

 strengthened in the planetary spectrum, and that all the 

 bands were relatively more intense in that part which was 

 produced by the light from the south equatorial band of the 

 planet's apparent disc. 



The appearance of the band at A. 618, which has been 

 previously observed in the spectra of the superior planets, 

 and of several new faint bands in the Jovian spectrum, 

 indicates the existence of a gas in the atmospheres of the 

 outer planets which does not exist at all, or only in much 

 feebler proportions, in the atmospheres of the inferior 

 planets. 



M. Millochau intends to prosecute this research further 

 at the Mont Blanc Observatory, where the clearer atmo- 

 sphere should permit of better results being obtained 

 (Bulletin de la Societe astronomique de France, November). 



