_336_. Helmholtz, 274, 308. Hero of Alexandria, 74. Herschel, 261. Hertz, Dr., 138. Hertzian waves, 138. Hot-water supply, 386. Hour-hand train in timepieces, _429_. Household water supply, and encloses sufficient air in the schools, he did not think you had heard it so much had happened was that it has returned with broken wings to fly? Against this notion of spontaneous generation, or.