john ericsson has looked to solar energy.dies and constructed what he calls solar engines. sunlight falling on the rooftops of philadelphia, he says, will power 5000 steam engines. other engineers are exploring different paths. some are trying to find a way to generate power from new fuels available such as petroleum and gas. the internal combustion engine is being tinkered and hammered into existence. ♪ ♪ the great-grandfather of all the automobile engines, airplane motors, and power mowers is getting a trial run. ♪ ♪ to his practiced ear, it sounds good. and it looks good. engineers are still confronting basic questions with every practical advance. what happens when energy changes from one form to another? what laws govern the transformation of heat into power? what is energy? questions the scientists of his day are working to answer. the electrical age is dawning. a new kind of light, the incandescent lamp is one of many inventions thomas edison would give to the world trade from generators, electricity can be sent as if