SCIENCE ADVANCES TO MEASUREMENT. 121 



employ. Space is measurable: hence Geometry. Force 

 and space are measurable : hence Statics. Time, force, and 

 space are measurable : hence Dynamics. The invention of 

 the barometer enabled men to extend the principles of me 

 chanics to the atmosphere ; and Aerostatics existed. &quot;When 

 a thermometer was devised there arose a science of heat, 

 which was before impossible. Such of our sensations as we 

 have not yet found modes of measuring do not originate 

 sciences. We have no science of smells ; nor have we one 

 of tastes. &quot;We have a science of the relations of sounds 

 differing in pitch, because we have discovered a way to 

 measure them ; but we have no science of sounds in respect 

 to their loudness or their timbre, because we have got no 

 measures of loudness and timbre. 



Obviously it is this reduction of the sensible phenomena 

 it represents, to relations of magnitude, which gives to any 

 division of knowledge its especially scientific character. 

 Originally men s knowledge of weights and forces was in 

 the same condition as their knowledge of smells and tastes 

 is now a knowledge not extending beyond that given by 

 the unaided sensations ; and it remained so until weighing 

 instruments and dynamometers were invented. Before 

 there were hour-glasses and clepsydras, most phenomena 

 could be estimated as to their durations and intervals, with 

 no greater precision than degrees of hardness can be esti 

 mated by the fingers. Until a thermometric scale was con 

 trived, men s judgments respecting relative amounts of 

 heat stood on the same footing with their present judg 

 ments respecting relative amounts of sound. And as in 

 these initial stages, with no aids to observation, only the 

 roughest comparisons of cases could be made, and only the 

 most marked differences perceived ; it is obvious that only 

 the most simple laws of dependence could be ascertained 

 only those laws which being uncomplicated with others, 

 and not disturbed in their manifestations, required no nice- 



