Jm the Advancement of Science. 101 



TactSj that we know what circumstances we ought to notice and 

 record ; and every labourer in the field of science, however hum- 

 ble, must direct his labours by some theoretical views, original 

 or adopted. Or if the word theory be unconquerably obnoxious, 

 as to some it appears to be, it will probably still be conceded, that it 

 is the rules of facts, as well as facts themselves, with which it is our 

 business to acquaint ourselves. That the recollection of this may 

 not be useless, we may collect from the contrast which Professor 

 Airy in his Report has drawn between the^ astronomers of our 

 own and of other countries. ^ In England," he says, (p. 184), 

 " an observer conceives he has done every thing when he has 

 made an observation." " In foreign observations," he adds, '* the 

 exhibition of the results, and the comparison of the results with 

 theory, are considered as deserving more of an astronomer's 

 attention, and demanding greater exertion of his intellect than 

 the mere observation of a body on the wire of a telescope." We 

 may indeed perceive in some measure the reason which has led 

 to the neglect of theory with us. For a long period astronomi- 

 cal theory was greatly a-head of observation, and this deficiency 

 was mainly supplied by the perseverance and accuracy of Eng- 

 lish observers. It was natural that the value and reputation 

 which our observations thus acquired for the time, should lead 

 us to think too disrespectfully, in comparison, of the other de- 

 partments of the science. Nor is the lesson thus taught us con- 

 fined to astronomy : for, though we may not be able in other 

 respects to compare our facts with the results of a vast and yet 

 certain theory, we ought never to forget that facts can only be- 

 come portions of knowledge as they become classed and connect- 

 ed : that they can only constitute truth when they are included 

 in general propositions. Without some attention to this cona-- 

 deration, we may notice daily the changes of the winds and 

 skies, and make a journal of the weather, which shall have no 

 more value than a journal of our dreams would have : but if 

 we can once obtain fixed measures of what we notice, and con- 

 nect our measures by probable or certain rules, it is no longer 

 a vacant employment to gaze at the clouds, or an unprofitable 

 stringing together of expletives to remark on the weather ; the 

 caprices of the atmosphere become steady dispositions, and we 

 are on the road to meteorological science. 



