INDEX. 99 



Velocities, comparative, 16 Water, volume and density of, 28 



Velocity of the tide, 84 Wave-lengths of light, 33 



Vibrations, no. of in notes, 36 Wind, pressure and velocity, 83 



Volume, measures of, 10 Wire gauge, 19 



Volumes, mensuration of, 7 Y\'ork, measures of, 20, 38 



Water, mass of vapour of, 31 Year, length of the, 8. 90 



tension of vapour of, 29 Young's modulus, 17 



