12 THE BORDERLAND OF SCIENCE. 



southern heavens, and Messier, the comet-seeker, made 

 a list of no less than 103. The star-cloudlets or nebulae 

 known when Sir W. Herschel began his researches, 

 amounted to less than 150. In the year 1786 that 

 astronomer began his contributions to the list of 

 known nebulas by sending a catalogue of no less than 

 1,000 of these objects to the Koyal Society. Three 

 years later he sent in a list of yet another thousand 

 nebulae; and in 1802 (when he was sixty-four years 

 old) another list, containing 500 of these objects. In 

 other words, during sixteen years this indefatigable 

 observer noted the places of more than sixteen times 

 as many of these celestial cloudlets as all preceding 

 observers had been able to record. Sir John Herschel, 

 having proposed to himself the task of completing at a 

 southern station the survey of the heavens which his 

 father had commenced, thought it necessary to prepare 

 himself for the work by re-surveying the northern 

 heavens. While thus engaged he discovered 500 

 nebulae which had escaped his father's notice. Then, 

 proceeding to the Cape of (rood Hope, he examined 

 those parts of the heavens which had been invisible 

 from his father's northerly observatory, and in 1847 

 communicated a list of 1,708 star-clouds discovered 

 during the progress of this survey. In all, Sir John 

 Herschel discovered no less than 2,208 nebulae, his 

 father having discovered 2,500. As the whole number 

 of known nebulae in our day amounts to but 5,200, it 

 will be seen that more than nine out of every ten 

 known nebulae were -discovered by the Herschels. 



