INDEX. 239 



Page. 



Wave velocities of light, unequal 155 



■\Vave velocities of sound, equal 15 j 



Waves, liquid lCn-6.3 



varieties of molecular movement in 157 



of condensation and rarefaction, defined 153 



unequal in length for different colors 171 



resultant of, in same plane 160 



resultant of, in normal planes 1C8 



interfering, must have common origin 168 



of I'ght and sound compared 171 



plane, considered as resultant of elementary spherical waves 15/ 



Wheatstone, his polar clock 143 



WoDastou, his discovery of flsed lines in the spectrum 125-2o 



Young, hypothesis of transverse vibrations suggested by 16:.i 



EREATA. 



q q 



Pat^e 110, line 5 from bottom, for — , „ . -r^ read / „ 77 i^> 



Page 112, line 16 from bottom, for mih read (m+l)st, in botli instances. 



