THE REFRACTOR AT DORPAT 127 



space than ever human being did before me. I have 

 observed stars, of which the light takes two millions 

 of years to travel to this globe.' " The Church is a 

 telescope that looks, or should look, even farther into 

 space and time. 



While Herschel was giving life and power to the 

 reflecting telescope, Dollond's followers in this country 

 and Fraunhofer in Germany were restoring the re- 

 fractor to the place from which it had been deposed. 

 In 1825 the finest refractor that, up to that time, the 

 world had ever seen was erected for Struve at the 

 expense of the Russian Government in Dorpat. The 

 tube was 13 feet in length, and the object-glass was 

 9 Paris inches in diameter. The weight of the 

 whole was about 3000 Russian pounds. Of his first 

 look through it Struve says: "I stood astonished 

 before this beautiful instrument, undetermined which 

 to admire most, the beauty and elegance of the work- 

 manship in its most minute parts, the propriety of its 

 construction, the ingenious mechanism for moving it, or 

 the incomparable optical power of the telescope, and 

 the precision with which objects are defined." 1 He 

 was proud of his assistant. He believed it to be the 

 equal of Herschel's 40-f eet reflector, and it was certainly 

 far more easy to work. With its help he continued 

 the work Herschel began. It appears, however, that 

 Herschel sometimes used a parabolical glass mirror of 

 7 -feet focal length instead of the metal mirror, 2 avoiding 

 by reflection the colours due to refraction. This 

 should be remembered to his credit. 



1 Astronom. Trans, ii. 94. 2 Phil. Trans, for 1803, p. 228, 



