CHAPTER XIIL ON FREE EXPANSION. PAGE Theory of a Fluid rushing through a Porous Plug . . . 209 Determination of the Dynamical Equivalent of Heat . . .211 Determination of the Absolute Scale of Temperature . . .213 CHAPTER XIV. DETERMINATION OF HEIGHTS BY THE BAROMETER. Principle of the Barometer .... The Barometer in a Diving Bell Height of the * Homogeneous Atmosphere * Height of a Mountain found by the Barometer . 217 218 220 221 CHAPTER XV. ON THE PROPAGATION OF WAVES OF LONGITUDINAL DISTURBANCE. Waves of Permanent Type.223 Velocity of Sound.. 228 CHAPTER XVL 'ON RADIATION. Definition of Radiation. 230 Interference.234 Different Kinds of Radiation ....... 237 Prevost’s Theory of Exchanges. 240 Rate of Cooling. 246 Effects of Radiation on Thermometers • . . . . 248
