THE PRINCIPLES OF SCIENCE. 



Natural History, is wholly unsuited to the purposes of 

 science. But of course when records relate to past events 

 like eclipses, conjunctions, meteoric phenomena, earth- 

 quakes, volcanic eruptions, changes of sea margins, the 

 existence of now extinct animals, the migrations of tribes, 

 floods, &c., we must depend upon traditions or records, 

 however unsatisfactory, and must endeavour to verify the 

 statements by the comparison of independent records. 



When extensive series of observations have to be made, 

 as in astronomical, meteorological, or magnetical observa- 

 tories, trigonometrical surveys, and extensive chemical or 

 physical researches, it is an advantage that the numerical 

 estimations and records should be executed by assistants 

 who are not interested in, and are perhaps unaware of, the 

 expected results. The record is thus rendered perfectly 

 impartial. It may even be desirable that those who per- 

 form the purely routine work of measurement and com- 

 putation should be unacquainted with the principles of 

 the subject. The great table of logarithms of the French 

 Eevolutionary Government was worked out by a staff of 

 sixty or eighty computers, most of whom were acquainted 

 only with the rules of arithmetic, and worked under the 

 direction of skilled mathematicians ; yet their calculations 

 were usually found more correct than those of persons 

 more deeply versed in mathematics 11 . In the Indian 

 Ordnance Survey the actual measurers have been selected 

 so that they shall not have sufficient skill to falsify their 

 results without detection. 



Both passive observation and experimentation must, 

 however, be generally conducted by persons who know 

 for what they are to look. It is only when excited and 

 guided by the hope of verifying a theory that the ob- 

 server will notice many of the most important points ; 

 and, where the work is not of a routine character, no 

 d Babbagc, 'Economy of Manufactures,' p. 194. 



