258 



NATURE 



[July 14, 1892 



distinct and natural to be taken for any impression other than 

 photographic. What these rivers, if we may use such a term, 

 are composed of is at present a subject of mere conjecture, 

 but the day is not far off when a very careful systematic study 

 will have to be undertaken to settle some of the questions that 

 have been recently raised in respect to our satellite s surface. 



Comet Swift (1892 March 6). — The ephemeris of this 

 comet for the ensuing week, taken from the Edinburgh Circular, 

 No. 28, is as follows : — 



1892. 



Berlin Midnight, 



Decl. log A. 



log r. 



July 14 o 58 26 +49 20 -8 



15 59 6 49 31*4 



16 o 59 44 49 41-8 0-2459 0-2776 o"i5 



17 I o 19 49 51-9 



18 o 52 50 1-8 



19 I 22 50 11-5 



20 I 49 50 21 -o 0*2488 0*2884 0'14 

 Brightness at time of discovery taken as unity. The comet 



les in the southern extremity of the constellation of Cassiopeia. 



Opposition of Mars. — All observatories which have the 

 necessary equipment are especially invited by the United States 

 Naval Observatory to join with them in making observations of 

 the coming opposition of Mars. Observations should commence 

 on June 20 to September 23, this period being divided into three 

 parts, the comparison stars for the first section being O, A. S. 

 20970, 7) Capricorni, 27 Capricorni, <p Caaricorni, Lacaille 

 8851, 41 Capricorni, D.M. - 20°, 6923, Lalande 42700. It may 

 be mentioned that observations made in accordance with the 

 special circular which the U.S. Observatory has issued will be 

 reduced by them. 



Sun-Spots. — Hivunel und Erde iox July contains two very 

 good photographs of the sun at the time of the great spot in 

 the month of February. They were photographed by Dr. 

 Lohse, at the Astrophysical Observatory at Potsdam, One was 

 taken on February 13 at loh., and shows the large group near 

 central transit with a smaller group on the limb ; while in the 

 other, the large group is nearer the western limb. A small 

 disc represents the relative size of the earth for comparison. 



Remarkable Prominences.— The sun's atmosphere this 

 year has been subject to many violent disturbances, indicated 

 to us by the presence of spots, prominences, &c. The spots, 

 with special reference to the February group, have already re- 

 ceived much attention, but not so with the prominences. From 

 a set of forty observations of the latter made between March i 

 and May 31, 1892, by M. Trouvelot, 23 of these, as he says, be- 

 longed to the most interesting type, i.e., eruptive. On April 6, 

 1892, there appeared an arched like prominence on the sun's 

 limb, extending through 12°, the length of its base being 

 144,932 and its height 92,664 kilometres ; to give an idea of 

 the size of this arch, it may be stated that as many as 22 globes 

 the size of our earth might have simultaneously passed under it. 

 At loh. 54m., on the Sth of the same month, a huge column of 

 .light, in shape rather like a candle flame, rose to a height of 

 115,830, extending, in a little over half-an-hour, to 169,884 

 kilometres. A prominence of far greater length, occupying 34° 

 of the solar limb, but of much less height than those mentioned 

 above, was visible on April 15. Its base covered 410,632 kilo- 

 metres, thus exceeding ten times the circumference of our earth. 



GEOGRAPHICAL NOTES. 



At the last meeting of the Council of the Royal Geographical 

 Society for the present session, it was unanimously agreed to 

 admit women as Fellows on the same terms as men. There is 

 nothing in the society's charter to limit the membership to men, 

 and the proposal of admitting ladies has been made several 

 times, and on the last occasion — two years ago — was nearly 

 carried. As there will not be another meeting of the society 

 until the opening of next session, the election of the first lady 

 F. R.G. S. cannot take place until November. 



The Annual Congress of the French Geographical Societies 

 meets this year at Lille in the first week of August, for the con- 

 sideration of questions relating mainly to France and its colonies. 

 The French Association for the Advancement of Science will 



hold its meeting at Pau, as we have already announced, in the 

 third week of September. Its Geographical Section will be 

 presided over by M. E. Anthoine, head of the French Map 

 Department and of Graphic Statistics under the Minister of the 

 Interior. In all departments of geography there is a remarkable 

 revival of interest among Frenchmen at the present time, 

 although the narrow or national aspect of the subject '.pre- 

 dominates over the wider or cosmopolitan. 



A curious account of the piratical Tugere tribe of New 

 Guinea has been published in most of the continental geographi- 

 cal journals on the authority of " an English medical missionary, 

 Dr. Montague," who was picked up by a Dutch war- vessel near 

 the boundary of Dutch and British New Guinea. This gentleman 

 told a remarkable narrative of his capture and imprisonment by 

 the Tugere, but as no English missionary of his name is known 

 to be in New Guinea, nor has any mission station been recently 

 raided by the Tugere, there is no doubt that some mistake has 

 been made. It is impossible that so serious an incident as the im- 

 prisonment of an English missionary could be unknown in this 

 country, and unless strong evidence were forthcoming, it is diffi- 

 cult to believe that such a thoroughly piratical people as 

 the Tugere could show the diligence in agriculture and the 

 relatively high civilization with which the story credits them. 



M. E. A. Martel continues his researches into the subter- 

 ranean geography of France. In March last he descended the 

 "unfathomable" Creux-Perce on the plateau of Langres, 

 proving it to be only 180 feet deep. It is a hollow in Jurassic 

 limestone, and, although open to daylight, forms a natural ice- 

 house, having a temperature of 28°F. when the external air was 

 at 58°. In June he examined the still more remarkable Creux 

 de Souci in the department of the Puy de Dome. It proved to 

 be a rounded cavity in recent basalt, 115 feet deep, having the 

 appearance of being formed by a great gas bubble. A stagnant 

 pool occupied the bottom of the pit, and above it the air was so 

 much impregnated with carbonic acid that a candle would not 

 burn. In this instance also the temperature fell as the distance 

 from the surface increased, that of the external air being 51°, of 

 the air at the bottom of the shaft 34°, and the water itself 34°"3. 

 The Paris Society of Commercial Geography recently awarded 

 a medal to M. Martel on account of the practical value of his 

 researches in leading to the regulation of the underground 

 drainage of Greece. 



EASTER ISLAND. 



"T^HE prehistoric remains of Easter Island make it for archseo- 

 -•- logists one of the most interesting islands in the Pacific. 

 They will therefore read with interest an elaborate paper in the 

 Report of the U.S. National Museum for 1888-89, which has 

 just been issued. The paper is entitled " Te PitoTe Henua, or 

 Easter Island," and is by William J. Thomson, Paymaster, 

 U.S. Navy. It records the results of researches made by Mr. 

 Thomson during a visit paid to Easter Island by the American 

 vessel, the Mohican, towards the end of 1886. The Mohican 

 anchored in the Bay of Hanga Roa on the morning of December 

 18, 1886, and remained till the evening of the last day of the 

 year, when she sailed for Valparaiso. Mr. Thomson and some 

 of his comrades, interested in the relics of a past phase of life in 

 the island, made the most of the short time at their disposal, 

 and his essay will certainly rank among the most important con- 

 tributions which have been made to our knowledge of the subject 

 with which it deals. 



He begins with a general account of Easter Island, and in this 

 part of his work has succeeded in presenting compactly and 

 clearly much valuable information. Of the geological features 

 of the island he says that they are "replete with interest." The 

 formation is purely volcanic, and embraces every variety per- 

 taining to that structure. The tufaceous lavas form the most 

 prominent element in the physiognomy of the island. To them, 

 with the action of the trade-winds and heavy rains, is due the 

 fact that Easter Island is surrounded by precipitous cliffs, rising 

 in some cases to a thousand feet in height. The formation is 

 extremely friable, and by the action of the elements enormous 

 masses are continually disappearing beneath the waves that 

 beat on the unprotected shore. Both on the coast-line and in 

 the interior there are many natural caves. Some of these are of 

 undoubted antiquity, and bear evidence of having been used by 

 early inhabitants as dwellings and burial-places. It is reported 



NO. II 85, VOL. 46] 



