OF NATURAL PHILOSOPHY. 129 



(124-.) But, it may be asked, if our measurement of 

 quantity is thus unavoidably liable to error, how is 

 it possible that our observations can possess that 

 quality of numerical veracity which is requisite to 

 render them the foundation of laws, whose distin- 

 guishing perfection consists in their strict mathe- 

 matical expression ? To this the reply is twofold. 

 1st, that though we admit the necessary existence 

 of numerical error in every observation, we can 

 always assign a limit which such error cannot pos- 

 sibly exceed ; and the extent of this latitude of error 

 of observation is less in proportion to the perfection 

 of the instrumental means we possess, and the care 

 bestowed on their employment. In the greater part 

 of modern measurements it is, in point of fact, ex- 

 tremely minute, and may be still further diminished, 

 almost to any required extent, by repeating the 

 measurements a great number of times, and under a 

 great variety of circumstances, and taking a mean 

 of the results, when errors of opposite kinds will, at 

 length, compensate each other. But, 2dly, there 



of the actual existing state of arts and knowledge at any 

 period might be transmitted to posterity in a distinct, tan- 

 gible, and imperishable form, if, instead of the absurd and use- 

 less deposition of a few coins and medals under the found- 

 ations of buildings, specimens of ingenious implements or 

 condensed statements of scientific truths, or processes in arts 

 and manufactures, were substituted. Will books infallibly 

 preserve to a remote posterity all that we may desire should be 

 hereafter known of ourselves and our discoveries, or all that 

 posterity would wish to know ? and may not a useless cere- 

 mony be thus transformed into an act of enrolment in a perpe- 

 tual archive of what we most prize, and acknowledge to be most 

 valuable ? 



