H Hahn, Otto Headend Heat Heat Pump Heinrich Hertz Helium Henry, Joseph Henry Switch Burnout - 8/28/95 Hertz (Hz) Hertzian Wave Hideki, Yukawa Holography Hopper, Kevin - Family Album Horizontally Collinear Antenna House Bill 813 HTML HTTP Huygens, Christiaan Hydraulic Machinery Hydrocarbon Hydrochloric Acid Hydrogen Hydrogen Bomb Hypertext Markup Language (HTML) Hypertext Transfer Protocol (HTTP)