PH 1 7 siOL OGICA L PHYSICS. 



Waves, Extent of, 218 



, Height of, 219 



, Length of, 298 



of muscular contraction, Re- 

 gistration of, 184 



of pulse, 225 



of sound, 418 



, Positive and negative, 217 



, Propagation of, 217 



-, Registration of, by graphic 



method, 217 

 Weight of g.is, 273 



, Standard of, 486 



Wenham's binocular prism, 370 

 Wheatstone's bridge, 138 

 rheostat, 135 



Wheatstone's revolving mirror, 



447 



Wheel barometer, 277 

 Wiedemann's boussole, 104 

 Wittich, Von, 267 

 Wollaston's camera lucida, 371 



doublet, 358 



experiment on freezing by 



evaporation, 475 



Young, 170, 296, 393, 433, 451 

 Young-Helmholtz' theory of colour 

 sensation, 343 



Ziemssen, 163 



Zeiss' microscope, 329 



CASSELL & COMPANY', LIMITED, BELLF SAUVAUE WORKS, LONDON, E.G. 



