706 ]'R()(}KES8 OF ASTRONOMY FOR 1891 AND 1892. 



a distaiice of 300.000,000 miles in front, and tbllowinu- it to a leii.u'th of 

 200,000,000 miles in the rear of its actual jtosition, or oceupying, if there 

 is no reason to sn]>pose the elongated meteor current discontinuous, 

 fully 500,000,000 miles in its observed length along the comet's path." 



SOLAR SYSTEM. 



Motion of tlir solur .sf/st<'iii. — Pi'of. Portei' has discussed the proper 

 motions of 1,340 stars contained in publication 12 of the Cincinnati 

 obser^•atory. Adopting I )r. Scluinfeld's method of di^ iding the stars into 

 four groups, according to the magnitude of their proper motions, he has 

 <'onlirmed Dr. >Stumpe's result that the proin'r motion of a star is an 

 index of its distance fioin us. The mean position of the ■•sun's way" 

 from his iigures is 281"^, 2 right ascension and +10".7 dediiiation. 



Dr. Vogel has also published the results <»f an in({uiry on this sui>ject 

 based on the measured velocities of stars in the line of sight. The 

 motion of fifty-one stars has been determined at Totsdain. and the ]>roba- 

 ble error in the measurement is below 1.10 geogra])hical miles, but the 

 resulting value of the ai)ex of motion, though the observations have 

 been discussed in various ways, is ii(»t in very satisfactory act'ord with 

 other investigations. If the stellar moti(Uis be treated cither with ecpial 

 weights, or weights approximately proportional to th()se assigned by 

 Dr. Vogel in his catalogue of jjioper motions, the coordinates <»f the 

 apex are 20(>o.l i 12c.O in right ascension, ami + 45^.0 rlr0°.2 in dec- 

 lination, with a velocity of 11.00 ^4^ l.So geogra])hical miles. 



SUN. 



Diameter of the sun. — A large number of heliometer ineasures of the 

 diameters of the sun and Venus made by the (Ternum transit of Yenus 

 ])arties in 1874 and 1882, incidental to the more important deternuua- 

 tion of the solar parallax, have been discussed by Dr. Auwers, who 

 finds for the mean result of the sun's diameter (thirty-one observers) 

 1.1>10".3, which difiers considerably from that adopted in the various 

 ephemerides; the Berlin Jahibuch, for instance, uses 1,922". 4, the ("on- 

 uaissance des Temps and British Nautical Abnauacl, 023". (i, and the 

 American ]*^phemeris 1,924".0. Dr. Auwers remarks that if the value 

 he finds is affected by irradiation it can only be too large, while 

 the adopted diameters are larger still. He announces that a change 

 will be made in the value used by the Berlin Jahrbuch in the volume 

 for 1895. 



Teinperatnre of the .sun. — The numerous attempts that have been 

 made to determine the temperature of the sun have led to the most 

 discordant results, the figures varying from 1,500^ to .-»,000,(I00^. The 

 method emph)yed, however, has ahvays been the same (that of Touil- 



