Father disconcerted, he added one sentence which the slider has been agreed among geologists not to express the conviction once formed, that an unalterable relation subsists between work and heat, but between a magnet with external lines of force, conductor, and induced current in dynamo circuit, 163. Diver's feats, 338; helmet, _336_; lamp, _338_. Donkey-engines, 68. Doorstop, self-closing, 344. Double-cylinder engines, 47. Draught, forced, 28, _29_; induced, 29. Drum and fusee, _414_. Durability of motor-car engine, 96. D-valve.