wheels, 375. Watt, James, 51, 69, 375. Welsbach incandescent mantle, 407. Westinghouse air-brake, 194, 195 , 197 ; George, 194. Wheatstone needle instrument, 128, 131; automatic transmitter, 135. Wind, why it blows, 323; action of on kites, 345; on sails, 346. Windmills, 375. Window, oval, in ear, 272; round, in ear, 272. Wireless telegraphy, 137; advance of, 145; receiver, 140, 141; syntonic, 143; transmitter, 138, 139 . Yale lock, 436 , 437 . Yellow spot, in eye, 251. Zech, Jacob, 414. Zeiss field-glasses, 260.
THE END.