78 DISCOURSE ON THE STUDY 



example, in our knowledge of the nature and causes 

 of volcanoes, earthquakes, the fall of stones from 

 the sky, the appearance of new stars and dis- 

 appearance of old ones, and other of those great 

 phenomena of nature which are altogether beyond 

 our command, and at the same time are of too rare 

 occurrence to permit any one to repeat and rectify 

 his impressions respecting them, we know little 

 more now than in the earliest times. Here our 

 tale is told us slowly, and in broken sentences. In 

 astronomy, again, we have at least an uninterrupted 

 narrative; the opportunity of observation is con- 

 stantly present, and makes up in some measure 

 for the impossibility of varying our point of view, 

 and calling for information at the precise moment 

 it is wanted. Accordingly, astronomy, regarded 

 as a science of mere observation, arrived, though 

 by very slow degrees, to a state of considerable 

 maturity. But the moment that it became a 

 branch of mechanics, a science essentially ex- 

 perimental, (that is to say, one in which any 

 principle laid down can be subjected to imme- 

 diate and decisive trial, and where experience does 

 not require to be waited for,) its progress suddenly 

 acquired a tenfold acceleration; nay, to such a 

 degree, that it has been asserted, and we believe 

 with truth, that were the records of all observ- 

 ations from the earliest ages annihilated, leaving 

 only those made in a single observatory*, during 

 a single lifetime f, the whole of this most perfect 

 of sciences might, from those data, and as to 

 the objects included in them, be at once recon- 

 * Greenwich. t Maskelyne's. 



