SCIENCE- G OS SIP. 



variability of Eros. Prof. Max Wolf has noticed 

 variations in others, particularly Tercidina, No. 345, 

 which appears regularly variable in 3 hours 49 

 minutes. 



Nebulae. — Professor Max Wolf, of Heidelberg, 

 calls attention to a portion of the heavens having 

 an area about equal to that of the Moon, 13' due 

 west of /8 Comae Berenices, containing 108 small 

 round nebulae. 



Great Suxspot Group. — A fine spot was ob- 

 served well round the limb on May 19th, after a 

 lapse of about ten weeks without spots on its face. 

 On May 20th and 21st a fine group of small spots 

 followed the large spot, the group having a length 

 of some 90,000 miles. 



The Henry Draper Medal has, we are pleased 

 to hear, been awarded by the United States 

 National Academy of Sciences to the distinguished 

 spectroscopist Sir William Huggins, who for the 

 past year has filled the presidential chair of our 

 own Royal Society. 



The Total Eclipse of the Sun was success- 

 fully observed at Mauritius, and a number of photo- 

 graphs taken both of the corona and spectrum. 

 The corona presented the expected minimum 

 form shown on another page, but was less brilliant, 

 yellowish, and not so clearly denned as last year. 

 The observers at Sumatra, from the lower stations, 

 were troubled by cloud, but from the mountains 

 made successful observations. 



"Cambkian Natural Observer/' the organ 

 of the Astronomical Society of Wales, for May, 

 1901, is to hand, containing much matter about 

 '• The New Star," " Meteors," etc. The opening 

 article is on the grave of Rev. T. W. Webb, to 

 whom, more than anyone else, by his papers in the 

 '■Intellectual Observer" and " Celestial Objects for 

 Common Telescopes, ' is due the great practical 

 interest in astronomical observation now in ex- 

 istence amongst amateurs. Mr. Arthur Mee, the 

 editor of " Cambrian Journal," recently found its 

 inscription already becoming unreadable, and that 

 making no reference to his great astronomical work. 

 There is no tablet to his memory even in his old 

 church. Mr. Mee suggests that those who owe 

 him such a debt of gratitude should raise some 

 more fitting monument to his memory. 



The Comet a 1901 seems to have been observed 

 in several places in Australia on April 23rd, also 

 by Halls at Queenstown in eastern Cape Colony, 

 when it was near Aldebaran. On 25th it is said to 

 have been near fi Piscium. On 26th from Yerkes it 

 is reported to have been 15° north of the Sun. On 

 May 2nd, 3 a.m., Mr. G. F. Chambers, of Eastbourne, 

 his wife and daughters seem to have observed its 

 tail. The next news comes from Arequipa in Peru, 

 where on the evening of May 2nd it was close 

 south of 10 Tauri. On May 4th at 6 h. 28-8 m. its 

 position from the Royal Observatoiy at the Cape 

 was found to be R.A. 3 h. 54 m. 29 s., Dec. 

 S. 0° 18' 27"; the daily motion R.A. + 14 m„ 

 and Dec. N. 13'. When reported it was so 

 brilliant that its nucleus could be seen with the 

 telescope for some time after sunrise, and it had a 

 triple tail about 10° long ; in other words, about as 

 long as from Rigel to Orion's belt. It is now rapidly 

 receding from the Earth, and decreasing in bright- 

 ness. It is well above the eastern horizon at the 

 time of sunset. On June 1st it will be a little 

 E.N.E. of 17 Monocerotis. 



CHAPTERS FOR YOUNG ASTRONOMERS. 



By Fiiank C. Dennett. 



(Continued from p. 376.) 



JUPITER'S SATELLITES. 



The equator of Jupiter is only inclined about 

 3° 5' to the plane of the ecliptic, therefore it 

 practically has no seasons. The satellites move in 

 orbits almost in the same plane as the planet's 

 equator, with the consequence that, with the excep- 

 tion of IV., they all pass through the cone of 

 shadow which Jupiter throws behind him, and so 

 suffer total eclipse at every revolution and also 

 pass in front of, or transit across the face of the 

 planet. From its greater distance, IV. sometimes 

 escapes both eclipse and transit, but usually follows 

 the same course as the rest. The eclipses are not 

 instantaneous, but the light gradually pales until 

 at last the satellite is lost to view. Before opposi- 

 tion the satellites pass into the cone of shadow 

 away to the west of Jupiter, I. and II. (') not 

 reappearing until they emerge from behind the 



eastern limb of the planet. After opposition, these 

 two satellites come right up to and pass behind 

 the western edge of the planet, and by-and-by 

 come, out of the shadow a little to the east of the 

 planet. Satellites III. and IV. may be seen to pass 

 into and out of the shadow, and then pass behind 

 the planet itself, or vice versa. When one of the 

 moons is hidden by the shadow, it is said to be 

 eclipsed, but when by the body of the planet it is 

 called an occultation. These phenomena may be 

 readily observed with small instruments. Some- 

 times, when satellites were suffering occultation in 

 1877, Todd and Ringwood, at Adelaide, thought 

 they could see the moons through the limb of the 

 planet. In 1863, on April 26th, Wray, with an 

 8-inch object-glass, saw II. apparently projected 

 within the limb for about 20 seconds. Revelations 

 of such phenomena as these are perhaps beyond 

 the powers of smaller telescopes. 



The most interesting observations, however, are 

 those of the transits of the satellites and their 



(1) Just at the time of quadrature— i.e., -when the planet is 

 90° distant from the Sun— II., for a brief interval, reappears 

 between eclipse and occultation. 



