50 



ASTRONOMICAL PHENOMENA AND PROGRESS. 



a velocity considerably greater than that of 

 the earth in its orbit. At this rate of motion 

 the star will describe a distance equal to that 

 which now separates it from the solar system 

 in less than 140,000 years. The velocities 

 with which certain other stars are receding 

 from the solar system are as follows : 



Beta Ursse Majoris 15 miles per second. 



Castor 24 ' 



Kigel 27 " 



Eegulus 83 ' 



Procyon 39 ' 



Spica 50 ' 



The following, on the other hand, are ap- 

 proaching the sun : 



Alpha Pegasi 22 miles per second. 



Arcturus 34 ' 



Vega 35 " 



Alpha Andromedse... 39 ' 

 Alpha Ursse Majoris... 40 ' 

 Gamma Leonis 66 " 



It will be noticed that Alpha and Beta of 

 the Great Bear (the two stars known as u the 

 pointers") are moving in different directions. 

 The former, which is nearer the pole, is ap- 

 proaching the sun ; the latter is receding from 

 it. 



Nebulce. M. Stephan, Director of the Mar- 

 seilles Observatory, has been recently devoting 

 special attention to the search for new nebulae. 

 The result has been the discovery of 400 of 

 these bodies, all of which had escaped the 

 notice of former observers. The fact that 

 they are generally small is favorable to the 

 accurate determination of their positions a 

 point of great importance for the future inves- 

 tigation of their proper motions. 



Supposed Changes in Messier 1 s Nebula No. 17. 

 This nebula, which was discovered by Mes- 

 sier nearly a century since, has lately been the 

 subject of critical study by Prof. Edward S. 

 Holden, of the Washington Observatory. It 

 was the object of these researches to deter- 

 mine whether the nebula has undergone any 

 sensible changes since the date of the earliest 

 trustworthy descriptions. The conclusion de- 

 rived from an elaborate discussion is that, 

 while the stars in and about the nebula have 

 retained their relative positions, the part of 

 the nebula known as the " Horseshoe " has 

 moved with reference to the stars, and that, 

 therefore, " we have evidence of a change going 

 on in this nebula.' 1 ' 1 This may be a change in 

 the nebula's internal structure, or it may be 

 " the bodily shifting of the whole nebula in 

 space in some plane inclined to the line of 

 sight." 



Variable Nebula in the Pleiades. Of this 

 interesting object the " Monthly Notices " of 

 the Royal Astronomical Society for February, 

 1876, says : 



The most remarkable object of the group is the 

 nebula around Merope. Discovered by M. Tempel 

 in 1859, it has also been seen by Profs. D' Arrest and 

 Schmidt, who were of opinion that the nebulosity 

 must be variable. On March 7, 1874, it consisted of 

 two portions, one of which was nearly concentric 



with Merope, but extending slightly toward th 

 east; the other, more luminous, was about seven 

 seconds of arc from the star, on the same parallel, 

 the diameter being about one second. From the 

 month of November, 187_4, to the end of February, 

 1875, the nebula was invisible, although it was 

 looked for on many occasions when the sky was 

 very favorable for the purpose. M. Wolf, therefore, 

 considers that this nebula is certainly variable, with 

 a moderately short period. 



KnobeVs Reference Catalogue of Astronomi- 

 cal Papers and Researches. The thirty-sixth 

 volume of the "Monthly Notices" of the 

 Royal Astronomical Society contains, in its 

 supplementary number, an elaborate and ex- 

 haustive catalogue of the literature of sidereal 

 astronomy. This catalogue, prepared by E. 

 B. Knobel, Esq., consists of a list of references 

 to all books, papers, and notes, relating to the 

 following subjects : 



1. Double Stars, including the Mathematical 

 Investigation of the Orbits of Binary Systems. 



2. Variable Stars. 



3. Red Stars. 



4. Nebulae and Clusters. 



5. Proper Motions of Stars. 



6. Parallax and Distance of Stars. 



7. Star Spectra. 



The list of references is derived mainly from 

 a systematic examination of the libraries of 

 the Royal Society and the Royal Astronomical 

 Society, the first of which is said to be pecul- 

 iarly rich and complete in the transactions of 

 scientific societies. The work was prepared, 

 the compiler informs us, " in the hope that 

 these references may be found useful to as- 

 tronomers in guiding them to the particular 

 literature giving information on the above- 

 mentioned branches of stellar astronomy, and 

 thereby reducing their labors in reading up 

 the subject to a minimum." 



Gold Medal of the Royal Astronomical So- 

 ciety. The gold medal of the Royal Astro- 

 nomical Society was awarded, in 1876, to M. 

 Leverrier, Director of the Paris Observatory, 

 for his theories of the four great planets, 

 Jupiter, Saturn, Uranus, and Neptune. Lever- 

 rier's theoretical investigations of the motions 

 of all the principal planets have now been pre- 

 sented to the Academie des Sciences. His 

 theories of the four inner planets were com- 

 pleted several years since, and for these, it 

 will be remembered, the medal of the society 

 was awarded him in 1868. At the annual 

 meeting in February, 1876, the president, 

 Prof. Adams, reviewed the labors of the dis- 

 tinguished mathematician, upon whom the 

 highest honor of the association had been a 

 second time conferred ; explained the grounds 

 on which the council had based their decision ; 

 and, in concluding, expressed to M. Leverrier 

 the deep interest with which astronomers had 

 followed him in his unwearied researches, and 

 the admiration which they had felt " for the 

 skill and perseverance by which he had suc- 

 ceeded in binding all the principal planets of 

 our system, from Mercury to Neptune, in the 

 chains of his analysis." 



