66 cosmos. 



an aperture only two feet in diameter, with a focal length 

 of twenty feet, has already heen the means of discovering 

 one satellite of Neptune, and an eighth of Saturn, besides 

 which two satellites of Uranus have been again distinguish- 

 ed. The new colossal telescope of Lord Rosse has an aper- 

 ture of six feet, and is fifty-three feet in length. It is mount- 

 ed in the meridian between two walls, distant twelve feet 

 on either side from the tube, and from forty-eight to fifty-six 

 feet in height. Many nebulae, which had been irresolvable 

 by any previous instruments, have been resolved into stellar 

 swarms by this noble telescope ; while the forms of other 

 nebulae have now, for the first time, been recognized in their 

 true outlines. A marvelous effulgence is poured forth from 

 the speculum. - 



The idea of observing the stars by daylight with a tele- 

 scope first occurred to Morin, who, with Gascoigne (about 

 1638, before Picard and Auzout), combined instruments of 

 measurement with the telescope. Morin himself says,* "It 

 was not Tycho's great observations in reference to the posi- 

 tion of the fixed stars, when, in 1582, twenty-eight years 

 before the invention of the telescope, he was led to compare 

 Venus by day with the sun, and by night with the stars," 

 but " the simple idea that Arcturus and other fixed stars 

 might, like Venus, when once "they had been fixed in the 

 field of the telescope before sunrise, be followed through the 

 heavens after the sun had risen, that led him to a discovery 

 which might prove of importance for the determination of 

 longitude at sea." No one was able before him to distin- 

 guish the fixed stars in the presence of the sun. Since the 



mixing of the metal, the contrivances adopted for casting and polishing 

 the specula and mounting the instruments. Abstr. of the Aslr. Soc, 

 vol. ix., No. 5, March, 1849. Vhe effect of Lord Rosse's six feet metal- 

 lic reflector is thus referred to (p. 120) : " The astronomer royal, Mr. 

 Airy, alluded to the impression made by the enormous light of the tel- 

 escope ; partly by the modifications produced in the appearances of 

 nebulae already figured, partly by the great number of stars seen even 

 at a distance from the Milky Way, and partly from the prodigious brill- 

 iancy of Saturn. The account given by another astronomer of the ap- 

 pearance of Jupiter was, that it resembled a coach-lamp in the tele- 

 scope; and this well expresses the blaze of light which is seen in the 

 instrument." Compare also Sir John Herschel, Outl. of Astr., 870. 

 " The sublimity of the ipectacle afforded by the maguificent reflecting 

 telescope constructed by Lord Rosse of some of the larger globular clus- 

 ters of nebula?, is declared by all who have witnessed it to be such as 

 no words can express. This telescope has resolved or rendered resolv- 

 able multitudes of nebulae which had resisted all inferior powers." 

 * Delambre, Hist, de V Astr on. Moderne, t. ii., p. 255. 



