Masterpieces of Science 



instruments to be used by the coming generation 

 of astronomers will surpass in perfection our 

 present ones as much as our new " apochromatic " 

 microscopes excel those that our fathers worked 

 with. 



It is unquestionable that photography, which 

 during the last twenty years has come forward 

 so rapidly as a means of astronomical investiga- 

 tion, is to become still more important. Already 

 there are immense fields in which it has not only 

 replaced visual observation, but has gone far 

 beyond the possibilities of vision, as, for instance, 

 in the study of stellar spectra, and in the pictur- 

 ing of comets and nebulae. But there are other 

 fields in which it cannot yet at all compete with 

 the eye of a good observer, as in the study of the 

 details of a planet's surface, the measurement of 

 close and difficult double stars, and in the so- 

 called "observations of precision," hitherto 

 made with meridian circles, transit instruments 

 and other instruments of the same general class. 

 The time is surely coming, however, and may be 

 near at hand, when photography will take pos- 

 session of these regions also. There is no reason 

 in the nature of things why it may not be possible 

 with improved plates and methods of develop- 

 ment, to photograph everything that the eye can 

 see with any instrument, and that more quickly 

 than the eye can see it, thus securing a record 

 that is permanent, authentic and free from the 

 personal bias of imagination and hypothesis, 

 which so seriously impairs the authority of many 

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