Slot, 226. Electroplating, 185, _186_. Electro-magnets, 117. Endolymph, 272. Engines, compound, 59; donkey, 68; double-cylinder, 47; internal-combustion, 87, 95; reciprocating, 44. Escapement of timepieces, 416; cylinder, _420_; lever, 421, _422_. Ether, 270. Eustachian tube, 276. Eye, human.