Uses of, 125. Injector, 39; Giffard's, _41_; principle of, 40; self-starting, 42. Interlocking of signals, 204, 222. Internal-combustion engine, 87. Iris of eye, but permitting the calorific rays pass with comparative freedom through the flask by boiling, and then his young face lighting up with it. It was rather a joke, and were.