ArRiL 1 6, 1 90S] 



NA TURE 



56; 



the Moiero ; and, finally, the exploration of the extreme 

 north of the Khatanga and Anabar. A inap of the 

 Khatanga and its upper branches shows the important 

 additions to geographical knowledge resulting from the 

 expedition, w-hich has proved that the supposed immense 

 lakes of that district do not exist. In addition, geological 

 information of great interest has been obtained, together 

 with important zoological and ethnographic collections. 



Prof, .^ristide Fiorextino, writing in the Rcndicoiiti of 

 the Lombardy Academy, directs attention to a school-room 

 experiment for showing the absorption of energy by an 

 acoustic resonator. He places the resonator in the neigh- 

 bourhood of a singing flame, and if the two are in unison 

 the vibrations of the flame instantly cease. The author 

 has further used the singing flame as a test for syntonised 

 resonation. Thus he has demonstrated in the case of a 

 gramophone horn that those tones are most readily 

 absorbed which are most strongly reinforced. The failure 

 to take account of this fact is no doubt partly the reason 

 why gramophone reproductions usually represent little more 

 than a caricature of the original music. The same records 

 are habitually snorted out through horns of all sizes and 

 shapes, whereas if the free vibrations of any particular 

 horn were reduced by the absorbing action of similar horns 

 in the manufacture of the records, the results would be 

 much better. 



Himmel und Erde for March contains the report of a 

 popular lecture on electric transmission of po.wer to 

 great distances, delivered by Prof. H. Gorges, of Dresden, 

 before the Scientific -Association of Berlin. The lecturer 

 deals in a clear manner with the generation of electric 

 current by the motion of a conductor through a magnetic 

 field, and shows how the modern dynamo is merely an 

 application of this principle. The generation of the power 

 to drive the machines is also treated, special attention 

 being given to the utilisation of the waste gases from 

 blast furnaces and to water power. Prof. Gorges believes 

 that the greatest future lies open to the simple alternating 

 as distinguished from the triphase current, and instances 

 the recent installation of the Ohlsdorf-Hamburg-Blankenese 

 electric raihvay as a step in this direction. The pressure 

 in this case is 6000 volts, w-ith 30,000 for transmission to 

 distant portions of the line. 



The London Geological Field Class excursions, con- 

 ducted by Prof. H. G. Seeley, F.R.S., for the study of 

 the Thames Basin, will commence on Saturday, May g. 

 Mr. J. W. Jarvis, St. Mark's College, Chelsea, S.W., is 

 the honorary secretary. 



A SECOND edition of the " Guide to the Archives of the 

 Government of the United States in Washington," by 

 Messrs. C. H. V. Tyne and W. G. Leland, has been pub- 

 lished by the Carnegie Institution of Washington. The 

 new issue has been revised and enlarged by Mr. W. G. 

 Leland ; the usual work of correcting errors, verifying 

 statements, supplementing the bibliographical data, alter- 

 ing classification when required by administrative changes, 

 and bringing the accounts to date, has been performed, 

 and in several cases the text has been much amplified. 



OUR ASTRONOMICAL COLUMN. 



The Recently Discovered S.^tellite of Jupiter. — The 

 observations made at Greenwich of the object near Jupiter, 

 recently discovered by Mr. Melotte, tend to confirm the 

 assumption that this object is in reality a satellite, the 

 eighth of the known Jovian satellites. 



In the .April number of the Observatory (N'o. 395, p. 177) 

 there appears a note which states that the observed posi- 

 tions, from January 27 to March 23, may be satisfied by 



NO. 2007, VOL. 77] 



the assumption that the satellite has a retrograde motion ; 

 the pole of the orbit plane lies in R.A. = 334° 48', 

 N. dec. = 56° 44'; distance from Jupiter 024 astronomical 

 unit ; daily motion about Jupiter, o^^ee. On February iS 

 it passed the minor axis of the apparent ellipse. The arc 

 yet observed is so small that any solution can only be 

 tentative, but it is hoped that sufficient observational 

 material has been gathered to ensure the re-discovery of 

 the satellite at the next favourable presentation. 



MUTO.^L OCCULT.4TIONS .^ND EcLIPSES OF JuPITER's 



S.iTELLiTES. — A partial occultation of Ganymede by Europa 

 was observed by Mr. Whitmell on January 25, the pheno- 

 menon lasting for some fifteen minutes. Prof. Oudeman 

 recently published some ephemerides for occultations 

 to take place in June next, but in No. 395 of the Observa- 

 tory (.April, p. 178) there appears a list of times at which 

 occultations will take place during the present month. In 

 the following extract the first Roman figure indicates the 

 eclipsed, the second the eclipsing, satellite : — .April 

 i7d. loh. 41m., II., III. ; i7d. i4h. 17m., II., I. ; 

 2id. i2h. 19m., IV., XL; 22d. gh. 41m., I\"., III.; 

 22d. iih. 27m., I., II.; 28d. I3h. 29m., IV., III. 



The Tr.^nsit of Mercury, November, 1907. — In No. 

 4238 of the Astronomische Nachrichten {March 9, p. 2iS> 

 M. Gautier records the results of the observations made, 

 at the Geneva Observatory, of the recent transit of 

 Mercury. Neither the bright outer ring nor the central 

 luminous spot w-as observed at any time during the transit. 

 Times of the contacts and the positions of Mercury re- 

 ferred to the sun's limb at different times during the 

 transit are given, and it is recorded that M. Pidoux, using 

 the Plantamour equatorial of 271 mm. aperture, found the 

 apparent diameter of the planet's disc to be 8"-4, ar» 

 amount sensibly less than that given by the ephemerides. 



P.iRALL.^x Observations. — The results of various 

 parallax observations made by Dr. Karl Bohlin at the 

 Stockholm Observatory appear in No. 4240 of the Astro- 

 nomische Nachrichten (March 23, p. 247). The first object 

 considered is a nebula, G.C. 1532, and the second an 

 adjacent star, Lalande 14512. Their respective parallaxes 

 are — o"-o36 and — o"-058, the Briinnow relative correc- 

 tions for the aberration constant being 4-o"-iS6 and 

 -l-o"-i49 respectively, corrections to w-hich Dr. Bohlin 

 directs especial attention on account of their magnitude. 

 The corresponding figures for Bossert 947 ( = Lalande 

 1S115) and 61 Cygni are -|-o".o85 and -^o"-363 for the 

 parallaxes, and +o".io2 and +o".048 for the corrections. 



Astronomical Photography with Portr.ait Lenses. — 

 Some good examples of celestial pictures taken with por- 

 trait lenses are reproduced in No. 187, vol. xlvi., of the 

 Proceedings of the .American Philosophical Society 

 (October-December, 1907, p. 417), in order to illustrate a 

 paper by Prof. Barnard on the subject of astronomical 

 photography. Prof. Barnard, in the first place, discusses 

 the great advantages accruing from photography in the 

 correct delineation of celestial objects, and then points out 

 the special suitability of the earlier portrait lenses of 

 large aperture for this purpose. This is followed by a 

 discussion of each of the objects shown, including nebul.-e, 

 star clusters, meteor 'trails, comets, &c. Most of the 

 pictures were taken with the lo-inch Brashear doublet of 

 the Bruce telescope. 



The Harvard College Observatory. — Prof. Picker- 

 ing's report of the work done at the Harvard College 

 Observatory during the year ended September 30, 1907, 

 is the si.xty-second of its series, and contains the usual 

 brief summary of an immense amount of work. With the 

 ii-inch Draper telescope, 356 photographs were secured, 

 making 17,035 in all, and with the S-inch Draper telescope 

 the taking of 611 photographs brought the total to 34,886. 

 The spectra of 456 stars, taken with the ii-inch instru- 

 ment, were studied and classified bf,' Miss Cannon', thus 

 bringing near to completion a catalogue of the spectra of 

 more than 1200 stars north of declination —30*^. 2710 

 stellar photographs were taken at .Arequipa, the total 

 numbers now taken with the 13-inch Boyden and 8-inch 

 Bache telescopes being 11,847 ^"'^ 38,224 respectively. 

 Other results, too numerous to mention here, are con- 

 tained in the report, and it 's announced that to private 



