NOTES TO BOOK VII. 319 



going on Sir John Herschel and Sir James South pub- 

 lished (in the PhiL Trans. 1824) accurate measures of 

 380 Double and Triple Stars, to which Sir J. South 

 afterwards added 458. Mr. Dunlop published measures 

 of 253 Southern Double Stars. Other Observations have 

 been published by Capt. Smyth, Mr. Dawes, &c. The 

 great work of Struve, Mensural Micrometricce, &c. con- 

 tains 3134 such objects, including most of Sir W. Her- 

 schel's Double Stars. Sir J. Herschel in 1826, 7 and 8 

 presented to the Astronomical Society about 1000 mea- 

 sures of Double Stars ; and in 1830, good measures of 

 1236, made with his 20-feet reflector. His paper in 

 Vol. v. of the Ast. Soc. Mem. besides measures of 364 

 such stars, exhibits all the most striking results, as to the 

 motion of Double Stars, which have yet been obtained. 

 In 1835 he carried his 20-feet reflector to the Cape of 

 Good Hope for the purpose of completing the survey of 

 Double Stars and Nebulae in the southern hemisphere 

 with the same instruments which had explored the nor- 

 thern skies, as mentioned in page 281. He returned 

 from the Cape in J 838, and is about to give the world 

 the results of his labours. Besides the stars just men- 

 tioned, his work will, I understand, contain from 1500 to 

 2000 additional double stars ; making a gross number of 

 above 8000, in which of course are included a number 

 objects of no great scientific interest, but in which also 

 are contained the materials of the most important dis- 

 coveries which remain to be made by astronomers. The 

 publication of Sir John Herschel's great work upon 

 Double Stars and Nebulae is looked for with eager inter- 

 est by astronomers. 



Of the observations of Nebulae we may say what has 



