ASTRONOMY. 9 



and by Liaponoff. A comparison of the previous measures 

 of distance with Nobile's indicates no motion. From the com- 

 parison of angles he concludes a probable revolution of stars 

 B, C, and D about A, so as to increase the angle. From this 

 it is inferred that the four stars of the trapezium are phys- 

 ically connected with each other. 



Professor Hall, of Washington, has observed the six stars 

 in the trapezium of Orion during two years, the different 

 combinations of the angles and distances of these stars bein^ 

 measured first with bright wires in a dark field, and again 

 with dark wires in a bright field. Each angle and distance 

 has been measured on at least six nights by each method. 

 Professor Holden has made a discussion and an adjustment 

 of these measurements by the method of least squares, from 

 which it appears that these six stars are probably physically 

 connected, as supposed by Xobile and others. 



Observations of the double stars, selected by Mr. Otto 

 Struve, Director of the Imperial Observatory at Pulkova, 

 for determining the personal errors of various astronomers, 

 have been made by Professor Hall, at Washington. This list 

 contains thirty stars, and on an average each star has been 

 observed on six nights. Professor Stone, of Cincinnati, is also 

 observing this list, as well as Professor Winnecke, of Stras- 

 burg, Baron Dembowski, etc. 



Mr. Burnham, of Chicago, quotes Struve's measures of 2 547, 

 which are (1831) p = 344.3, s 4. 25", and notes measures of 

 his own (1S7S) p=. 9.1, s = 2.46". This appears to be in 

 rapid motion. 



Mr. Burnham has just sent to the Royal Astronomical So- 

 ciety, for publication, his double-star observations of 1877-78. 

 These comprise: I. A catalogue of 251 new double stars, with 

 measures; II. Micrometrical measures of 500 double stars. 

 Of the 251 new double stars, 75 pairs are less than 1" distant, 

 and 59 pairs are distant from 1" to 2". Over 1400 micro- 

 metrical measures have been made, each of 5 angles of posi- 

 tion and 3 measures of double distance. This great labor 

 was entirely one of love, and the observations were all made 

 after a day spent in business occupations. Considered in this 

 way, the number of measures becomes as remarkable as their 

 excellence. 



A 2 



