400 



NATURE 



[August 25, 1892 



phonically any telegrams addressed to them. A copy of the 

 telegram is sent at the same time. The number of telegrams 

 thus sent by telephone in 1889 was 371,000 ; in 1890 it grew 

 to 440,000, To facilitate the development of telephonic rela- 

 tions the country is divided by Government into a number of 

 circles, containing several towns provided with central offices 

 communicating with each other by means of a double wire. 

 Thus the inhabitants of a small town like fJeyst are able to 

 speak with Bruges, Blankenburgh, Ostend, Middlekerke, and 

 Nieuport. The system is being extended wherever clients are 

 probable, and the telephone now enters largely into Belgian 

 habits. 



In the south-east of the valley of Mont Dore (Puy-de-D6me 

 is a curious natural formation in the basalt, called the Creux- 

 de-Souci. A crater-shaped depression about 80 ft. wide com- 

 municates by a central hole with a larger circular cavern, 1 70 ft. 

 diameter, the bottom of which is occupied by a small lake 

 with about 10 ft. of water. The shape is like that of two cups 

 with bases opposed ; the lower one the larger. From an 

 examination of the place this summer by M. Martel and some 

 friends {La Nature), it appears that carbonic acid is plentiful in 

 the cavern. Several times they went down by rope-ladder, 

 hoping to use a boat lowered previously ; but they could not 

 get below about 13 ft. from the water (which was about 70 ft, 

 from the orifice) ; they experienced headache, progressive suffo- 

 cation, &c., while matches and candles went out. The cavern 

 is probably closed ; there is no sign of a stream ; nor are there 

 any stalactites. The lake is merely fed by water filtering 

 through the basalt ; after heavy rain this is considerable. The 

 temperature is exceptionally low, which M. Martel explains 

 thus : Snow lies several months on the neighbouring ground, 

 and when this melts in spring its water penetrates into the 

 Creux-de-Souci at a temperature near o°C. Thus the air is 

 <:ooled, and, being denser than that outside it, accumulates 

 below ; it is not renewed from above. No air-current was 

 observed. The accepted view that there is water communication 

 with Lake Pavin (about 270 ft. lower) is considered a mistake. 

 It would be interesting, M. Martel says, to make methodical 

 observations, in different seasons, both as to the carbonic acid 

 and the temperature. 



Mr. C. Davies Sherborn asks us to state that the grant 

 from the British Association, stated by us as being made towards 

 "Index to Plants," &c., was really towards "Index Generum 

 et Specierum Animalium," a work which has already been 

 referred to on two occasions in Nature — May 15, 1890, and 

 July 2, 1 89 1. 



The additions to the Zoological Society's Gardens during the 

 past week include a Japanese Ape {Macacus speciosus, <J ) from 

 Japan, presented by Mr. H. H. Jacobs ; two Rhesus Monkeys 

 {Macacus rhesus, $ ? ) from India, presented by Mr. R. Dod- 

 man and Mr. C. W. Emlyn respectively ; a Macaque Monkey 

 {Macacus cynomolgus, $ ) from India, presented by Mr. R. 

 Rocca ; two Crowned Lemurs {Lemur coronatus) from Mada- 

 gascar, purchased ; a Common Cormorant {Phalacrocorax carbo), 

 British, presented by Capt. Salvin ; two Spotted-sided Finches 

 Amadina lathdini) from Australia, purchased ; twenty-five 

 Cambayan Turtle Doves ( Turtur senegalemis) from East Africa, 

 deposited by General Mathews ; three Cambayan Turtle Doves 

 {Turtur senegalensis) from East Africa, presented by General 

 Mathews ; three Hardwickes Mastigures ( Urotnastix hardwicki) 

 from India, purchased ; a Robben Island Snake {Coronella 

 phocarum) from South Africa, presented by Miss M. Ruther- 

 ford ; a Nilotic Monitor ( Varanus niloticus) from East Africa, 

 presented by Gen. Mathews ; a Nilotic Monitor ( Varanus 

 niloticus) from East Africa, presented by Mr. Frank Finn, 

 F.Z.S. ; two Smooth-clawed Frogs {Xenopus eavis) ixom"£,^%\. \ 

 NO. II 9 I, VOL. 46] 



Africa, presented by Mr. Frank Finn, F.Z.S. ; a Common Boa 

 {Boa constrictor) from South America, presented by Messrs. F. 

 Sander and Co. •, four Indian Wild Swine {Sus cristatus), born 

 in the menagerie. 



OUR ASTRONOMICAL COLUMN. 



Nova Auriga. — In Wolsingham Observatory Circular, 

 No. 33, it is stated that Mr. H. Corder having informed the 

 Rev. T. E. Espin that the Nova Aurigae had increased, it was 

 examined August 21, and found to be 9'2, spectrum mono- 

 chromatic ; one intense line (500?). 



The Opposition of Mars.— At the Lick Observatory, up 

 to the middle of August, many of the supposed canals on Mars 

 discovered in 1877 by Schiaparelli were mapped, but none of 

 them seemed to be double. On the night of the 17th inst., 

 however, Profs. Schaberle, Campbell, and Hussey made three 

 entirely independent drawings, each showing the canal marked 

 Ganges on Schiaparelli's map to be distinctly double, and thus 

 confirming in 1892 Schiaparelli's discovery of 1877. 



Thermal Absorption in the Solar Atmosphere.— In 

 Astronomische Nachrichten, Nos. 3105-06, Mr. E. B, Frost sets 

 forth the results of his observations with reference to thermal 

 absorption in the solar atmosphere. As the paper is of con- 

 siderable length, we will only concern ourselves with the broad 

 results, leaving our readers to look up the details for themselves. 

 The instrument — made by Mr. Frost himself, and used through- 

 out the experiments — was a double thermopile, or, rather, two 

 thermopiles, of considerable length ; and the back junctions,: 

 after being carefully insulated and imbedded in sealing-wax, 

 were inserted in the two ends of a brass U-shaped tube, the 

 front faces of the piles projecting a little out of the tube, while' 

 their back parts were in contact in the middle. To ensure an; 

 equality of temperature at the two back junctions, this part 

 the tube was enveloped in a cylinder filled with water, th 

 eliminating practically accidental thermo effects in the met 

 of the thermopiles, Mr, Frost's original intention was to em- 

 ploy both these piles, one for receiving the projected image 

 of the sun, and the other for the direct rays, but, as he 

 became acquainted with the " disproportionately greater inten- 

 sity of the latter," he was obliged to employ as a screen a thin 

 silk gauze, thus using this pile as a counterpoise to eliminate 

 such effects as air currents, reflected radiations, &c. 



Let us deal first with the photosphere. The following table 

 shows the differences between observation and theory. The 

 column headed O is obtained from a curve based on the 

 observations, that of C is the result of theory and gives the 



values of I : I„ as obtained from the ratio ^— = 7^ 



lo e-f . 



p represents the distance of the point observed from the centre 

 of the sun (radius = 100), and Q the angle at the sun's centre 

 between the line to the observer and the radius to the point 

 observed. 



P e o 



ICO'O 



99 '9 



99-4 



98-4 



96-3 



93 -6 



89-8 



846 



77-9 



68 -o 



(39) - - - - 

 The differences in the last column might, as Mr. Frost says, 

 be somewhat reduced by the introduction of another constant m 

 the formula, but even then sufficient difference would remain to 

 indicate the inability of the formula to cope with the present 

 conditions. 



In the attempt to ascertain whether there was a difference in 

 the thermal conditions for the poles and the equator, taking 

 points equidistant from the centre of the sun's disc, the con- 

 clusion Mr. Frost draws is that there is none. The difference 

 between the two hemispheres also he finds "to be exceeding 

 small, if real." "With regard to the spots he says, "A rather sur- 

 prising result of these observations was that spots are occasionally 

 relatively warmer than the surrounding photosphere." Whether 

 the position of the spot on the disc had anything to do with it is 



