2':2 



NATURE 



[April 2t, 1910 



Encke's Comkt, 1895-1908. — The Monthly Notices for 

 March (vol. Ixx., No. 5, p. 429) contains a discussion by 

 Dr. Backlund of the motion, brightness, &c., of Encke's 

 comet during the period 1895-1908. In the first place, he 

 deduces elements fitting the observations of 1895, 1901, 

 and 1904, and shows that the acceleration of the mean 

 motion was not constant during the period under dis- 

 cussion. This leads to a discussion of the various causes 

 which might produce the diminution observed, and of the 

 probable time at which such causes, or cause, were, or 

 was, effective. Excluding solar electrical forces, it seems 

 probable that the resistance encountered is a meteoric 

 swarm in the neighbourhood of perihelion, and the de- 

 crease of the acceleration must be attributed rather to 

 the diminution of the density of the resisting medium than 

 to changes in the comet itself. If, however, the variation 

 of the acceleration is held to be actually connected with 

 the maxima of solar activity, tangential electrical forces 

 are admissible in explaining it, and the problem becomes 

 indeterminate. 



Various causes of the comet's fluctuations in brightness, 

 e.g. an alteration in shape, and therefore in surface pre- 

 sented, produced by the solar tidal action, are discussed, 

 but no explanation is entirely satisfactory, and the ques- 

 tion is left open. 



Dr. Backlund then investigates the relation between 

 Wolf's comet of 1907 and Encke's comet, and the possi- 

 bility of capture by Jupiter. Whilst not proving that the 

 comet was captured, he shows the possibility of such 

 capture having taken place within the past 5700 years. 



The Spectra of the Major Planets. — In Bulletin No. 

 42 of the Lowell Observatory Dr. V. M. Slipher publishes 

 further descriptions and reproductions of the spectra of 

 the major planets. The photographs were taken with 

 plates especially sensitised for the red end of the spectrum, 

 and show a wealth of detail between D and A. Com- 

 parative exposures on the south equatorial dark belt and 

 the bright equatorial region of Jupiter indicate no reason 

 for supposing that the darker portions of the planet are 

 those lying the deeper. The spectrum of Saturn is gener- 

 ally similar to that of Jupiter, but there is a strong band 

 in the latter at \ 646 which is absent, or nearly so, in 

 the former ; as the others are of the same intensity, this 

 points to the existence of a constituent in Jupiter's atmo- 

 sphere which is absent in that of Saturn. No trace of 

 the planetary bands is found in the spectra of Saturn's 

 rings, and there is no indication of any atmosphere about 

 the rings. 



A comparison of the spectra of the four m.ijor planets 

 shows that in Neptune all the bands seen in the other 

 three are intensified, except that at X 646, which appears 

 to be peculiar to Jupiter. The evidence for hydrogen 

 absorption in the atmospheres of Uranus and Negtune is 

 very slight, and the intensification of C and F is not 

 copied by the hydrogen bands at W 4341 and 4102, so far 

 as an ordinary eye examination can determine, so that, 

 at the best, the identity can only be considered probable. 

 Of the other bands photographed scarcely anything is 

 known, but it is shown that the very strong band at X 619 

 is not identical with one in the spectra of red stars, as is 

 sometimes stated. 



The Intrinsic Brilliancy of the Sun. — In a previous 

 paper Dr. Nordmann estimated that the intrinsic brilliancy 

 of the sun was 319,000 decimal candles per sq. cm. 

 (Nature, March 3, p. 29), but he now finds that one 

 of his data, owing to an ambiguity in Mijller's text, is 

 incorrect. He has, therefore, re-calculated his value, and 

 gives, in No. 13 of the Comptes rendus (March 29), 

 100,500 decimal candles per sq. cm. 



THE CARNEGIE INSTITUTION OF 

 WASHINGTON. 



'T'HE eighth annual report of the Carnegie Institution of 

 Washington, describing the work of the institution 

 during the year 1909, has now been published. It is a 

 well-illustrated volume of 259 pages, dealing with the work 

 of administration, the investigations carried out under the 

 auspices of the institution, the various publications, the 

 expenditure recommended for 1910, and additional sugges- 



NO. 21 12, VOL. 83] 



tions. .Subjoined are extracts from the report of the presi- 

 dent of the institution upon the progress of the difterent 

 scientific departments. ! 



Among the more important events of the year are the ! 

 completion of the administration building in Washington, 

 the establishment and active operation of the observator> 

 of the department of meridian astrometry in Argentina, 

 the construction and putting into commission of the non- 

 magnetic ship Carnegie of the department of terrestrial 

 magnetism, and the inauguration of the project for the 

 publication of an edition of the master-works on inter- 

 national law. .Attention is directed to the fact that with 

 these, and with the previously established larger enter- 

 prises under way, the accumulated income of the institution 

 has been exhausted, and that there will be no room for 

 further expansion under current income in the immediat-- 

 future. 



In the last annual report a summary statement of the 

 work of the institution up to October 31, 1908, was given. 

 A more detailed study of the scope and geographical range 

 of this work shows that investigations have been carried 

 on under the auspices of the institution in more than thirty 

 different fields of research, and that these investigations 

 have extended to more than forty different countries. The 

 total number of volumes of publications issued directly by 

 the institution is 141, with an aggregate of about 35,000 

 pages of printed matter. For the larger departments of 

 investigation there are now provided two astronomical 

 observatories, five laboratories, and one ship. A complete 

 list of the equipments of these establishments includes fifty- 

 eight buildings and eight smaller craft in addition to the 

 ship Carnegie. The total amount of funds granted for ex- 

 penditure is 864,000/. The total amount expended is 

 825,900/. 



At the date of the preceding annual report the depart- 

 ment of meridian astrometry was engaged in the construc- 

 tion of a temporary observatory at San Luis, Argentina. 

 The instrumental equipment for this was shipped from the 

 Dudley Observatory, Albany, N.Y., in December, 1908. 

 After safe transportation to San Luis, the constants of the 

 meridian transit, the principal instrument used, were care- 

 fully re-determined, proving to the highest order of pre- 

 cision that this instrument suffered no injury in trans- 

 shipment. With this indispensable preliminary investiga- 

 tion completed, the work of stellar observation was begun 

 in .April. 1909, and is now going on at a rapid rate. 



The following list shows the departments of investiga- 

 tion to which the larger grants were made by the trustees 

 and the amounts allotted from those grants by the 

 executive committee during the year : — 



£ 



Department of Botanical Research 6,400 



Department of Economics and Sociology ... 3. .500 



Department of Experimental Evolution 5,800 



Department of Historical Research 4,100 



Department of Marine Biology 3,ooo 



Department of Meridian Astrometry 6,000 



Department of Terrestrial Magnetism 12,000 



Department of Terrestrial Magnetism, vessel... 15,000 



Geophysical Laboratory ... 9,000 



Horticultural work of Luther Burbank ... 2,000 



Nutrition Laboratory 5'°°° 



Solar Observatorv 20,800 



Division of Publications ... ... ... ••• 900 



The various investigations of the botanical research 

 department have been successfully continued during the 

 past year. Among these, the experiments of the directoi 

 in the production of mutants in plants seem destined t< 

 play a fundamental rSle in the determination of th« 

 absorbing biological question of the derivation of species 

 Equally important in this same line are the experiment; 

 with beetles of Prof. Tower, for which vivaria are now 

 maintained at the Desert Laboratory at Tucson and a 

 the Marine Biological Laboratory at Dry Tortugas, Florida 



The work of the department of experimental evolutioi 

 presents a double interest in furnishing evidences at onc( 

 of the evolution of organic forms and of the evolution o 

 a science. The history of biological science, like thi 

 historv of most sciences in their earlier stages, has been 

 and still is, marred to some extent by heated controversy 

 But all this is destined to disappear with the rise of biolog: 



