ASTKONOMY. 



135 



to assume that the atmosphere of this planet is extremely attenuated. 

 The chief spots are invariably visible, and the phenomena occasionally 

 observed are rather to be imputed to the vagaries of our own atmos- 

 phere than to that of Mars. 



" Jupiter and Saturn are doubtless enveloped in dense vapors shroud- 

 ing their real surfaces from terrestrial eyes. Their markings are atmos- 

 pheric, though in some cases very durable, and constantly undergoing 

 changes of aspect and displacements of position by longitudinal cur- 

 rents. On Mars a totally different nature of things prevails. Here 

 the appearances described are absolute surface markings displaying 

 none of the variations which are so conspicuously displayed on Jupiter. 

 It seems to me that the very pronounced character of the 

 markings and their great permanency are quite opposed to the idea that 

 the planet is surrounded by a dense cloud-laden atmosphere." 



Dr. Lohse has used, in observing Mars, a double-refracting prism, 

 achromatized for the extraordinary ray ; this prism, placed before the 

 ocular of the telescope, brings out more sharply the details of the 

 planet's surface by reducing the polarized light reflected from its at- 

 mosphere. 



Satellites of Mars. — Professor Hall was able to observe the outer 

 satellite, Deimos, on four evenings in March, 1886, but the inner satel- 

 lite was seen only once, and was then so faint that no measurements 

 could be made. Both little bodies were near their predicted places. 



The minor planets. — Eleven minor planets were added to the list 

 in 1886, the last one bearing the number 261; the brightest was of the 

 eleventh magnitude. Seven of the new-comers belong to Dr. Palisa, 

 making the total number discovered by him fifty-seven. Dr. Peters has 

 now discovered forty-six and Dr. Luther twenty-three. 



The dates of discovery and the names, as far as assigned, are given 

 in the following table : 



Minor planets discovered in 1886. 



No. 



254 

 255 

 256 

 257 

 258 

 259 

 260 

 261 

 262 

 263 

 264 



Names. 



Augusta .. 

 Oppavia .. 

 Walpurga 



Silesia 



Tyche . . . . 

 Aletlieia . 

 Hubert a . . 

 Prymuo .. 

 Valda .... 

 Dresda . . . 

 Libussa... 



Date 

 of disQOvery. 



March 31, 1886. 



....do 



April 3 



April 5 



May 4 



June 28 



October 3 



October 31 . . . . 

 November 3 . .. 



...do 



December 22 . . 



Magui- 

 tude 

 at dis- 

 covery. 



13.5 



13.5 



12.5 



13 



11.3 



12 



13.5 



11.2 



12 



12 



11.5 



Discoverer. 



J. Palisa 



....do 



....do 



....do 



R. Luther . . . 

 C. H. F. Peters 



J. Palisa 



C. H. F. Peters 



J. Palisa 



. ... do 



C. H. F. Peters 



Observatory. 



Vienna. 

 Do. 

 Do. 

 Do. 



Diisseldorf. 



Clinton. 



Vienna. 



Cliuton. 



Vienna. 



Do. 

 Clinton. 



