304 



NA TURE 



[January 26, 1893 



Comet Brooks (November 19, 1892).— The following 

 ephemeris of Comet Brooks is due to Ristenpart, and is given 

 in Astronomische Nackrichten, No. 3142 : — 



This comet, which will be found to be in the constellation of 

 Andromeda, will lie about 3J° to the south of i Andromedse on 

 January 27. 



Photographic Absorption of our Atmosphere. — The 

 question of the degree with which our atmosphere absorbs 

 photographic rays has become very important owing to the adop- 

 tion of photography, so that any work enlightening us on this 

 subject is anxiously listened to. Prof. Schaeberle, who has been 

 making investigations in this direction, has just completed a 

 memoir which is being published by the University of California, 

 but in the meanwhile he has issued a table setting forth simply 

 the final results. The absorption in the following table is ex- 

 pressed in photographic magnitudes, and must be added to the 

 unknown atmospheric absorption at the zenith. 



Z. £). Phot. Z. D. Phot. 



, Absorp. „ Absorp. 



5 0-00 50 0-44 



10 001 55 0-56 



15 0-04 60 0-71 



20 0-07 65 089 



25 o*ii 70 112 



30 016 75 ... 1-45 



35 — o'2i 80 1-94 



40 ... ... ... 0-28 85 2-68 



45 •• 0-35 90 5-00 



Harvai^d College Observatory, — The forty-seventh 

 annual report of this Observatory, by Prof. Pickering, opens 

 with a reference to the death of Mr. George B. Clark, to whose 

 "genius for mechanical devices, indomitable perseverance, and 

 devotion to the interests of the observatory, we are indebted for 

 the success of many of our most useful instruments." Of the 

 most important matters mentioned in the report are the per- 

 manent establishment of an observing station in South America, 

 where the unsteadiness of the air is for the most part eliminated, 

 the construction of a suitable building for the housing of photo- 

 graphs and the approaching completion of the Bruce photo- 

 graphic telescope. The work done with the various instruments 

 during this period has been considerable. With regard to the 

 Draper telescope, as many as '2777 photographs have been 

 taken, while those taken with the Bache instrument number 

 nearly 2000. The Boyden department, which is situated at 

 Arequipa, in Peru, has been making great progress, the results 

 of which have been frequently inserted in Astronomy and Astro- 

 physics. The eight surfaces of the objective of the Bruce tele- 

 scope have, as Prof, Pickering informs us, been ground and 

 polished, and the results up to the present, according to tests 

 made on a star, are very satisfactory. This instrument, when 

 finished, is destined foi the Arequipa station. 



Solar Observations at Rome. — Prof. Tacchini has issued 

 the results of the observations made with regard to the distribu- 

 tion in latitude of the solar phenomena at the Royal Observatory 

 during the third semester in 1892. From the tabulated state- 

 ment which he gives the following facts may be gathered. 



With regard to the eruptions, these phenomena seem to be 

 quite local to the equatorial regions, the relative frequency 

 being 0*667 ^nd 0-333 for the north and south latitudes re- 

 spectively. The spots, faculse, and eruptions have their maxima 

 nearly at the same distance from the equator both north and 

 south, the zones being (± 20°, ± 30°), but the maxima for the 

 prominences extend further north, about latitudes 60° north and 

 south. Prof. Tacchini remarks that in the equatorial zone 

 ( -t- 20° — 20°), where the maxima of faculse, spots, and eruptions 

 are observed, a feeble relative frequency in the prominences is 

 noted, which shows us that we must consider a large num- 

 ber of prominences as the result of conditions " bien differentes 

 par rapport a celles qui determinent la production des taches 



NO. 12 13, VOL. 47] 



dans la photosphere," whilst the prominences are formed 

 simply in the .solar atmosphere. As a case in point, he men- 

 tions an observation made on August i of last year, of a cloud 

 which, starting at a distance of 264", rose to 364" without any 

 corresponding alteration at the surface. 



The Total Solar Eclipse, April 15-16, 1893.— Writing 

 to M. Flammarion about the scientific expedition sent by the 

 Brazilian Government to study the region of the central plateau 

 and to select a site for the proposed new capital. Dr. Cruls, 

 the Director of the Observatory at Rio de Janeiro, adds the 

 following note: — "About the total eclipse of April 16. Will 

 France send any one to observe it ? I beg you to make known 

 through the Revieiv {VAstronomie) that the Brazilian Govern- 

 ment is willing to send a warship to Ceara, on which foreign 

 astronomers who wished to observe the phenomenon could find 

 a passage." 



GEOGRAPHICAL NOTES. 



A change has been made in the arrangements for the ex- 

 pedition to Lake Rudolf referred to on p. 235, vol. xlvii. The 

 expedition is to travel by the Tana river instead of the Juba, 

 although its ultimate destination is the same, and Lieutenant 

 Villiers, instead of accompanying it, has joined Sir Gerald 

 Portal's mission to Uganda. 



Mr. H. J. Mackinder, M.A., Reader in Geography at 

 Oxford, delivered the first of a course of ten educational 

 lectures, under the auspices of the Royal Geographical Society, 

 on the relation of geography to history, on the 20th inst. The 

 attendance was largely composed of teachers and University 

 Extension students, to whom special terms were offered. The 

 lecturer treated of "the Theatre of History," tracing the 

 development of accurate geographical knowledge from the 

 earliest times in a series of brilliant generalisations. He dwelt 

 upon the contrast between the knowledge of early Greek 

 geographers regarding the true shape of the earth, and their 

 habitual representation of the regions known to them in a cir- 

 cular form. In the middle ages, amongst the half-learned, the 

 map of the known world was elevated to the highest place, the 

 figure of the globe was forgotten, and the doctrine of a flat 

 earth gained currency. At the geographical renaissance the 

 I map was adapted once more to the sphere, and the discoveries 

 of Columbus and his contemporaries resulted directly. 



The suggestion of Mr. Joseph Thomson to bestow the name 

 of Livingstonia (vol. xlvii. p. 160) on the British sphere of 

 influence north of the Zambesi, in spite of its singular propriety, 

 has, we fear, failed to convince the authorities in charge of the 

 region, who, it appears, have decided to adopt the cumbrous 

 and scarcely accurate title of British Central Africa. 



M, Mizon's second expedition to Adamawa has been stopped 

 on the Benue by the breakdown of his steamers, and the sudden 

 failing of the water, he being left without means of progress 

 about two-thirds of the way between Lukoja and Yola. 



The French flag has been formally hoisted on the little islands 

 of St. Paul and New Amsterdam in the South Indian Ocean, 

 midway between the Cape of Good Hope and Australia. St. 

 Paul is an interesting instance of a volcanic island, the extinct 

 crater of which forms a wide sheltered harbour communicating 

 with the sea by means of a single narrow channel. It was one 

 of the French stations for observing the transit of Venus in 1874. 

 French fishermen from Reunion had practically taken posses- 

 sion of the islands in the early part of the century, but the 

 fishing-grounds have long been abandoned. 



Mr. B. V. Darbishire, M.A. (Oxon.), has been appointed 

 Cartographer to the Royal Geographical Society. He has had 

 the advantage of preliminary training in Germany, and under 

 the Reader in Geography at Oxford, 



THE APPROACHING ECLIPSE OF THE SUN, 

 APRIL 16, 1893.1 



T HAD the honour, two and a half years ago, of describing 

 -*■ to you the total eclipse of the sun of December 22, 1889, 

 which I had been to observe in the Salut Isles, French Guiana. 

 In spite of very unfavourable atmospheric conditions I was then 



' Address to the Astronomical Society of France, on November 2, 1892, 

 by M. De la Baume Pluvinel, translated by A. Taylor. 



