PORTION OF THE COSMOS. MULTIPLE STARS. 203 



stern-trabanten (1778), and Diss. de novis in Coelo sidereo 

 Phseriomenis (17 79)," 80 multiple stars observed by him are 

 described, among which 67 are less than 32" apart. The 

 greater number were new discoveries of his own made with 

 the excellent eight-feet telescope of the Manheim Mural 

 quadrant ; " some are still amongst the most difficult objects, 

 and which can only be shown by powerful instruments ; as 

 p and 71 Herculis, f Lyrse, and w Piscinca." Mayer, in- 

 deed (as, however, was still done long after his time), only 

 measured distances in Eight Ascension and Declination by 

 his meridian instrument; -and from his own observations, 

 and those of earlier astronomers, showed changes of position, 

 from the numerical values of which he erroneously did not 

 deduct what (in particular cases) belonged to the proper 

 motions of the stars ( 336 ). 



These slight but memorable beginnings were followed by 

 William HerscheFs colossal work on multiple stars. It em- 

 braces a period of more than 25 years ; for although the first 

 table of HerscheFs double stars was published 4 years after 

 Mayer's Memoir on the same subject, yet HerscheFs obser- 

 vations go back to 1779, or even, if we include his investi- 

 gations on the trapezium in the great nebula in Orion, to 

 1776. Almost all that we now know relative to the several 

 classes of double stars has its origin in Sir William HerscheFs 

 work. He not only gave in the catalogues of 1782, 1783, 

 and 1804, the positions and angular distances apart of 

 846 double stars ( 337 ), the majority of which were discovered 

 exclusively by himself ; but what is much more important than 

 the increase of number, he exercised his acute sagacity and 

 true spirit of observation on all that relates to the paths, 

 supposed periods of revolution, luminous intensity, contrast 



