Never, been able to focus sharply objects at distances of air, 288, 289; of rods, 287; of strings, conditions regulating, 278. _Viper_, the, 86. Virag, Pollak--high-speed telegraphy, 136. Vitreous humour, 246. Voltage, 121, 161. Vowel sounds, 308. Wasborough, Matthew, 51. Watches, first, 412. Water cock, _365_; engines, 375; gauge, 35.