OF NATURAL PHILOSOPHY. S53 



likely to exercise over the future. It is only by 

 condensing, simplifying, and arranging, in the most 

 lucid possible manner, the acquired knowledge of 

 past generations, that those to come can be enabled 

 to avail themselves to the full of the advanced point 

 from which they will start. 



(386.) One of the means by which an advanced state 

 of physical science contributes greatly to accelerate 

 and secure its further progress, is the exact know- 

 ledge acquired of physical data, or those normal 

 quantities which we have more than once spoken 

 of in the preceding pages (222.) ; a knowledge 

 which enables us not only to appretiate the accuracy 

 of experiments, but even to correct their results. 

 As there is no surer criterion of the state of science 

 in any age than the degree of care bestowed, and 

 discernment exhibited, in the choice of such data, so 

 as to afford the simplest possible grounds for the ap- 

 plication of theories, and the degree of accuracy 

 attained in their determination, so there is scarcely 

 any thing by which science can be more truly bene- 

 fited than by researches directed expressly to this 

 object, and to the construction of tables exhibiting 

 the true numerical relations of the elements of 

 theories, and the actual state of nature, in all its dif- 

 ferent branches. It is only by such determinations 

 that we can ascertain what changes are slowly and 

 imperceptibly taking place in the existing order 

 of things ; and the more accurate they are, the sooner 

 will this knowledge be acquired. What might we 

 not now have known of the motions of the (so-called) 

 fixed stars, had the ancients possessed the means of 

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