June 23, 1892] 



NA TURE 



79 



The British Consul in Hainan, in his last report, says that 

 during the past year he has made two journeys in that island, 

 one to certain prominent hills near Hoihow, known as the 

 " Hummocks," which lie fifteen miles to the west, on the road 

 to Ch'eng-mai, the other a gunboat cruise to Hansui Bay. The 

 people at both these places, and presumably all along the north- 

 west coast, though believing themselves Chinese, speak a 

 language which is not only not Chinese, but has a large per- 

 centage of the words exactly similar to Siamese, Shan, Laos, or 

 Muong. The type of the people, too, is decidedly Shan, with- 

 out the typical Chinese almond eye. At one time (looo years 

 ago) the Ai-lau or Nan-chau Empire of the Thai race extended 

 from Yun-nan to the sea, and the modern Muongs of Tonquin, 

 like the Shans of the Kwangsi province, the ancestors of both of 

 which tribes belonged to that empire, probably sent colonies 

 over to Hainan ; or the Chinese generals may have sent 

 prisoners of war over. It is certain that some at least of the 

 unlettered, but by no means uncivilized, tribes in the central 

 parts of Hainan speak a type of language which is totally 

 different from that spoken by the Shan-speaking tribes of 

 the north-west coast. Yet the Chinese indiscriminately call 

 all the non-Chinese Hainan dialects the Li language. The 

 subject, Mr. Parker says, is one of great interest, well worth 

 the attention of travellers. It was his intention to pursue the 

 inquiry when making a commercial tour of inspection round the 

 island, but his transfer to another post compels him to abandon 

 his scheme. 



The additions to the Zoological Society's Gardens during the 

 past week include a Brown Capuchin {Cebus faitteilus) from 

 Guiana, presented by Mr. Edward Solomon ; two Black Swans 

 {Cygnus atratus) from Australia, presented by Lady William 

 Osborne Elphinstone ; a Greater Spotted Woodpecker {Dendro- 

 copus major), two Common .Cormorants {Phalacrocorax carbo), 

 British, presented by Sir H. B. Lumsden, K.C.S.I. ; a 

 Greater Sulphur-crested Cockatoo {Cacatua galerita) from 

 Australia, presented by Mr. F. R. Brown ; two Common Rheas 

 {Rhea americana) from the Argentine Republic, deposited ; an 

 Erxleben's Monkey [Cerco/>it/iecus trxlebeni i ) from West Africa, 

 a Victoria Crowned Pigeon (Goura victoria ? ) from the Island 

 of Jobie, two Wonga-Wonga Pigeons {Leucosarcia picata) from 

 New South Wales, a Rosy-billed Duck {Melopiana peposaca <i ) 

 from South America, twenty Common Teal (Querquedula 

 crecca), European, purchased; a Thar {Capra jemlaica), two 

 Burrhel Wild Sheep {Ovis burrhel (J 9 ), an Axis Deer {Cervus 

 axis 6), four Temminck's Tragopans [Ceriornis iemmincki), a 

 Himalayan Monaul {Lophophorus impeyanus), bred in the 

 Grardens. 



OUR ASTRONOMICAL COLUMN. 



Colours on thk Surface of Mars.— During the last op- 

 position of Mars a series of observations was made by Prof. 

 Pickering with the object of determining the general colour 

 of this planet's disk, and that of the various markings 

 distributed over its surface. In a preliminary account 

 of this work which he has contributed to the June num- 

 ber oi Astronomy and Astro- Physics, we are made acquainted 

 with some of the observed facts, which will be read with keen 

 interest, as we are nearing a time when like observations can be 

 repeated. The instruments used were the 12-inch and 15-inch 

 at Cambridge, and the 13-inch at Arequipa, Peru. With the 

 two former sixty paintings were made, together with sixty-six 

 uncoloured drawings, and with the latter some of the more 

 recent observations were undertaken. The general light from 

 the planet, although usually termed ruddy, was found to lie 

 about midway between that of a candle and electric light of 

 equal brilliancy, being somewhat bluer than the former and 

 redder than the latter. 



Great difficulty seems to have been found in matching 

 Mars's colour in the day and night time, the presence or 



NO. II 82, VOL. 46] 



absence of the bluish white light reflected from the atmo 

 sphere bringing about a great difference in the colour of the pig- 

 ments used. The colour finally settled upon may be represented 

 by equal parts of dragon's blood and sienna. The ruddiness, as 

 the limb was approached, gave way to a distinct yellow tint, 

 due perhaps to atmospheric absorption, an effect, as Prof. 

 Pickering remarks, which is quite at variance with the action of 

 our own atmosphere. In addition to these colours grays and 

 greens have been noticed, indeed at times the greens have been 

 more intense than the red. The grey objects were found, 

 when the seeing was very good, to have a slightly yellowish 

 tinge about them, but when viewed by daylight a browner tint 

 more accurately represented their colour. 



Numerous observations were made also with the intention of 

 determining the colour of those parts more darkly tinted, and 

 the colour of the canals ; but Prof. Pickering only mentions that 

 there were indications of slight colour alterations, reserving his 

 opinion on these points in order not to bias those of other ob- 

 servers, who will be able in the coming opposition to examine 

 this planet's surface from this point of view. 



During the months of July and August the planet, excepting 

 for its low altitude, will be most favourably situated for obser- 

 vation, the opposition occurring on August 4, when its 

 distance from the earth will be about 35,000,000 miles. 



Observations of the Moon. — The Monthly Notices 

 (vol. Hi., No. 7) contains, besides the observations of the right 

 ascensions and north polar distances of the moon made during 

 the year 1891 at the Kadcliffe Observatory, Oxford, a com- 

 parison of these results, with the tabular places taken from 

 Hansen's lunar tables. The two suppositions on which these 

 results are compared are, as Mr. Stone says : (i) that the mean 

 times found in the usual way from the sidereal times at mean 

 noon given in the Nautical Almanac, were not altered in scale, 

 or affected with any different systematic errors of determination, 

 by the adoption in 1864 of a different ratio of the Julian year 

 of 365i "mean solar days" to the mean tropical year; (2) 

 that the "mean times " which accurately correspond to a given 

 "sidereal time of a meridian " were necessarily changed in 1864 

 by the use of a different ratio of the "Julian year," and there- 

 fore of the " mean solar day " to the mean tropical year, to fix 

 the tabular right ascensions of the clock stars at the meridian 

 transits. It is from these tabular right ascensions of the clock 

 stars that the observed right ascensions are deduced by the aid 

 of clocks ; and the right ascensions thus found are finally 

 rendered definite by the direct reference to the positions of the 

 sun deduced from the north polar distances and obliquities of 

 the ecliptic. 



During the period included in the years 1847 to 1863 the 

 mean annual error in longitude of Hansen's tables amounted 

 to — 1"85, no regular law of increase being indicated. 

 Taking the case of those observations made up to the end of 

 last year, the mean annual error, as shown in the third table, has 

 steadily increased from the year 1863 at an average rate of 

 o"75 per annum, the errornow amounting to as much as I9"'30. 

 If the corrected argument be used for taking out the mean 

 annual error of Hansen's tables during the same period, this 

 value becomes - i"*49, which differs from -l"'85 (the value 

 for the preceding period) by a quantity which in such a case is 

 very small. 



A Planet beyond Neptune? — For some time it has been 

 thought that in all probability our sun is accompanied by one 

 or two other planets which lie outside the orbit of Neptune. 

 The idea gained a considerable footing in many minds after 

 Prof. Forbes's paper, which he read in i88o before the Royal 

 Society of Edinburgh, his prediction being based on cometary 

 aphelia positions. In order to investigate this question more 

 fully, Mr. Isaac Roberts, having obtained the necessary approxi- 

 mate positions of these hypothetical bodies, undertook to make 

 a search for them, employing the method of long e-xposure 

 photography. The result of this search he communicates to the 

 May number of the Monthly Notices. 



The probable position indicated by Prof. Forbes lay be- 

 tween R.A.'siih. 24m. and I2h. 12m., with declinations o^ o' to 

 6" o' north ; and over this region Mr. Roberts took two sets of 

 eighteen plates, each plate covering more than four square 

 degrees, the exposure being of 90 minutes' duration. A close 

 examination of the plates showed that, in Mr. Robsrts's words, 

 "no_ planet of greater brightness than a star of the fifteenth 

 magnitude exists on the sky area herein indicated." 



