6o6 



NATURE 



{Oct. 1 8, 1883 



was therefore due to some secondary effect produced by the 

 wind pressure, and not directly by the pressure itself, and it was 

 to the ripples produced on the surface, which disturbed the 

 wave motion, that the speedy breaking was to be attributed. It 

 was, however, a direct result of the theory that the ripples de- 

 pended on surface tension for their propagation, and could not 

 exist in large amount on the oiled surface. It was also evident 

 that the hold of the wind on the wave was greatly decreased by 

 the absence of ripples, and thus the oil acted both to prevent the 

 wind having much effect on the surface, and also to modify the 

 motion of the water in the wave. 



Prof. Stokes read a paper by Dr. Huggins On Coronal Pho- 

 tography without an Eclipse. In a paper read before the Royal 

 Society some time back, Dr. Huggins had shown that it was 

 possible by isolating, by means of properly chosen absorbing 

 media, the light of the sun in the violet part of the spectrum to 

 obtain photographs of the sun surrounded by an appearance dis- 

 tinctly coronal in its nature. These researches have been con- 

 tinued, using a reflecting telescope by the late Mr. Lassell, and 

 a film of silver chloride as the sensitive plate on which the 

 photograph is taken. These plates are sensitive to the violet 

 light only, and therefore it was unnecessary to use absorbing media 

 which had proved a source of difficulty to sift the light. Fifty 

 photographs in all were taken and examined afterwards by Mr. 

 Wesley, who made drawings of them for the paper. — Dr. Ball, 

 who was in the chair, examined some of the plates, and spoke 

 of the interest and importance of this communication. 



Prof. Schuster read a paper On the Internal Constitution 0/ the 

 Sun. He had calculated the volume of the sun from its mass, 

 assuming that it consisted of a gas subject to gaseous laws and in 

 the state of convectional equilibrium discussed by Sir William 

 Thomson. The paper showed that, if the rates of the specific 

 heats of the gas were less than I '2, the volume of the sun would 

 be immensely larger than at present, while, if greater than 20, 

 the sun's volume would be far smaller than it is. The result 

 that the rates of the specific heats must lie between VZ and 2'o 

 is so far in agreement with received theories of the constitution 

 of the sun. 



Notes on some recent Astronomical Experiments at High 

 Elevations on the Andes, by Ralph Copeland. — These experi- 

 ments were made during the first half of the present year at the 

 cost of the Earl of Crawford. At La Puz, in Bolivia, 12,000 

 feet, with the full moon in the sky, ten stars were seen 

 in the Pleiades with the naked eye. and also two stars in 

 the head of the Bull that are not in Argelander's Urano- 

 metria Nova. The rainy season lasted roughly until the end of 

 March, after which there was a large proportion of fine sky. 

 At Puno, on Lake Titicaca, 12,600 feet, with a 6-inch tele- 

 scope mounted on a lathe headstock, a number of small planetary 

 nebula;, and some stars with very remarkable spectra, were found 

 by sweeping the southern part of the Milky Way with a prism 

 on Prof. Pickering's plan. The most remarkable stars had 

 spectra reduced almost to two lines, one near D, and the other 

 beyond F, with a wave-length of 467 mm., and apparently 

 identical with a line in some only of the northern nebulas as ob- 

 served by Mr. Lohse and Mr. Copeland. A few close double- 

 stars were also found, amongst them $ Muscat. 



At Vincocaya, 14,360 feet, the solar spectrum was examined 

 with a somewhat damaged instrument. The chief fact noted 

 was the relative brightness of the violet end of the spectrum. 

 With a small spectroscope several lines were seen beyond H and 

 H 2 . The prominences were visible with almost equal facility in 

 C, D 3 , F, and H s . Attempts to see the corona proved futile, 

 nor were the prominences seen otherwise than in the spectro- 

 scope, the only difference being that the slit could be opened far 

 wider than down at the sea-level. A most careful examina- 

 tion of the zodiacal light failed to show even the slightest 

 suspicion of a line in its spectrum, which was continuous although 

 short. Both at Puno and Vincocaya the air was very dry the 

 relative humidity there and at Arequipa, 7700 feet, being as low 

 as 20 per cent. At Vincocaya the black bulb at one time stood 

 above the local boiling point, while the wet bulb was coated with 

 ice. The author was of opinion that an observatory might be 

 maintained without discomfort up to 12,000 feet, or even a 

 little higher— the night temperature falling only slightly below 

 the freezing point. At greater elevations the thermometer 

 falls 1° for every 150 feet of height, the barometer sinking about 

 o'l inch for the same change. At 15,000 feet it will thus be seen 

 that arduous winter conditions are reached without any very 

 material gain in the transparency of the atmosphere. From 

 information received it seems possible to maintain a station for a 



short time in the early summer as high as 18,500 feet ; later on 

 the rains set in and render travelling very difficult. Railway 

 and »teamboat communication enable instruments of any size and 

 weight to be carried as high as 14,660 feet, and as far as the 

 Titicaca shore of Bolivia. 



OUR ASTRONOMICAL COLUMN 



Pons' Comet. — The following ephemeris is deduced from 

 MM. Schulhof and Bossert's provisionally corrected elements: — 



At Greenwich Midnight 



, c - R-A. Decl. Log. distance from 



I883 - h. m. s. . Earth. Sun. 



Oct. 16 ... 16 39 53 ... +55 377 ... 02653 ••• 0-2723 



18 ... — 42 19 ... 55 137 



20 ... — 44 57 ... 54 500 ... 0-2520 ... 02603 

 22 ... — 47 47 ... 54 26-5 



24 ... — 50 48 ... 54 33 ... 0-2378 ... 0-2472 



26 ... — 54 1 .. 53 404 



28 ... 16 57 27 ... 53 17-7 ... 0-2226 ... 0-2340 



3° ■•■ "7 1 5 •■■ 52 55 - 3 

 Nov. 1 ... — 4 56 ... 52 33-1 ... 0-2065 ••■ 0-2204 



3 ... — 9 O ... 52 II-2 



5 ... — 13 18 ... 51 494 ... 01894 ... 0-2062 



7 ... — 17 49 ... 5' 2 7'6 



9 ... ■ — 22 37 ... 51 5-9 ... 0-1710 ... 0-1916 



11 ... — 27 40 ... 50 44-1 



13 - — 3 2 59 - 5° 22 '° ■■■ ''5J3 - 01764 



•S ••■ — 38 35 - 49 59° 



17 ... — 44 29 ... 49 368 ... 0-1303 ... 0-1607 



19 ... — 50 42 ... 49 134 



21 ... 17 57 16 ... +48 49-1 ... 0-1079 •■■ o''445 



The intensity of light will be three times greater on November 21 

 than on October 16, and will increase until near the middle of 

 January. According to the experience of 1812, we might expect 

 it to draw within naked-eye vision at the beginning of December, 

 but it is not likely to attain a brightness at all comparable with 

 the conspicuous comets of the last few years. It may rather be 

 anticipated that when best seen, its light will be nearly that of 

 stars of the third magnitude. We are of course assuming the 

 comet not to have undergone material change since its last ap- 

 pearance. On the morning of August 18, 1812, the Paris astro- 

 nomers have the note : — " La comete commence a etre visible a 

 l'ceil nu ; son noyau assez brillant, est enveloppe d'une chevulure 

 et sa queue est d'environ ij° a 2°." Employing MM. Schulhof 

 and Bossert's final orbit, we find that at the hour of observation, 

 about 2h. 30m. a.m. G. M.T., the comet was in R. A. 1 14° 24', 

 Decl. +40° 27', distant from the earth 1-4713, and from the 

 sun 0-9449, so that the intensity of light, expressed in the usual 

 way, would be 0'52, which corresponds to that on December I 

 in the present year. On the morning of September 14 it was 

 remarked: — "La queue de la come'e est divisee en deux 

 branches paralleles ; sa longueur parait d'environ 3 degres." 

 At 4I1. 30m. a.m. G.M.T. the comet was dis'ant from the earth 

 1-2324, and from the sun 0-7778, whence, the earth's radius- 

 vector being 1-0051, the angle at the comet was 54° 29', and 

 with Newcomb's s^lar parallax, the real length of the tail, if 

 extending as most usual in the direction opposite to the sun, 

 would be 7,600,000 miles, or a little over. 



In announcing the discovery of this comet by Pons at Mar- 

 seilles on July 20, 1812, Zach remarked (Monatliche Corre- 

 spondenz, xxvi. 270) that it was the sixteenth (? fourteenth) comet 

 which he had independently discovered within ten years. So 

 indefatigable a worker in this direction well deserves that his 

 name should be permanently associated with at least one of his 

 discoveries, and none presents itself as affording a more fitting 

 case than the comet of 1S12. 



Swift's Cometary Object. — It would appear from un- 

 successful search at European and American observatories that 

 Mr. Swift must have been mistaken in supposing he had ob- 

 served a comet in the places published in Astron. Nach., 

 No. 2541. 



The Cordoba Observatory. — Dr. B. A. Gould, director 

 of the Observatory at Cordoba, passed through London last 

 week en route for South America, after attending the meeting of 

 the " Astronomisches Gesellschaft " at Vienna, and that of the 

 International Standard Commission at Paris. We learn from 

 Dr. Gould that the printing of the second volume of Cordoba 

 Zones is nearly completed in London. The attention of this 



