PEACTICAL PHYSICSCHAPTER IMEASUREMENTFundamental Units1. Introductory. A certain amount of knowledge about familiar things comes to us all very early in life. We learn almost unconsciously, for example, that stones fall and balloons rise, that the teakettle stops boiling when removed from the fire, that telephone messages travel by electric currents, etc. The aim of the study of physics is to set us to thinking about how and why such things happen, and, to a less degree, to acquaint us with other happenings which we may not have noticed or heard of previously.Most of our accurate knowledge about natural phenomena has been acquired through careful measurements. We can measure three fundamentally different kinds of quantities, - length, mass, and time, - and we shall find that all other measurements may be reduced to these three. Our first problem in physics is, then, to learn something about the units in terms of which all our physical knowledge is expressed.2. The historic Table of Contents CHATTER PAGE; I MEASUREMENT 1; Fundamental Units Density; II PRESSURE IN LIQUIDS11; Liquid Pressure beneath a Free Surface Pascal's Law The Principle of Archimedes; III PRESSURE IN AIR26; Barometric Phenomena Compressibility and Expansibility of Air Pneumatic Appliances; IV MOLECULAR MOTIONS49; Kinetic Theory of Gases Molecular Motions in Liquids Molecular Motions in Solids; V FORCE AND MOTION57; Definition and Measurement of Force Composition and Resolution of Forces Gravitation Falling Bodies Newton's Laws; VI MOLECULAR FORCES90; Elasticity Capillary Phenomena Absorption of Gases; VII WORK AND MECHANICAL ENERGY105; Definition and Measurement of Work Work and the Pulley Work and the Lever The Principle of Work Power and Energy; VIII THERMOMETRY ; EXPANSION COEFFICIENTS 128 Thermometry Expansion Coefficient of Gases Expansion -; of Liquids and Solids Applications