INSTRUMENTS USED IN MEASUREMENT. 



BY Measurement, for scientific purposes, is meant the measure- 

 ment of quantities. In each special subject there are quantities 

 to be measured ; and these are very various, as may be seen from 

 the following list of those belonging to geometry and dynamics. 



Geometrical Quantifies. 

 Lengths 

 Areas 

 Volumes 



Angles (plane and solid) 

 Curvatures (plane and solid) 

 Strains (elongation, torsion, shear). 



Ore n instances of Motion. Properties of Bodies. 



Time Mass 



Velocity Weight 



Momentum Density 



Acceleration Specific gravity 



Force Elasticity (of form and volume) 



Work Viscosity 



Horse-power Diffusion 



Temperature Surface tension 



Heat. Specific heat. 



Notwithstanding the very different characters of these quanti- 

 ties, they are all measured by reducing them to the same kind of 



