initiated the commercial success that solar power desperately needed, we will never know. However, the Sun Power Co. can boast a certain technical maturity by effectively synthesizing the ideas of its predecessors from the previous 50 years. The company used an absorber (though in linear form) of Tellier and Willsie, a reflector similar to Ericsson's, simple tracking mechanisms first used by Mouchout and later employed by Eneas, and combined them to operate an engine specially designed to run with solar-generated steam. In effect, Shuman and his colleagues set the standard for many of the most popular modern solar systems 50 to 60 years before the fact.The Most Rational Source The aforementioned solar pioneers were only the most notable inventors involved in the development of solar thermal power from 1860 to 1914. Many others contributed to the more than 50 patents and the scores of books and articles on the subject. With all this sophistication, why couldn't solar mechanical technology blossom into a viable industry? Why did the discipline take a 50-year dive before again gaining a measure of popular interest and technical attention?First, despite the rapid advances in solar mechanical technology, the industry's future was rendered problematic by a revolution in the use and transport of fossil fuels. Oil and coal companies had established a massive infrastructure, stable markets, and ample supplies. Also, besides trying to perfect the technology, solar pioneers had the difficult task of convincing skeptics to see solar energy as something more than a curiosity. Visionary rhetoric without readily tangible results was not well received by a population accustomed to immediate gratification. Improving and adapting existing power technology, deemed less risky and more controlled, seemed to make far more sense.Finally, the ability to implement radically new hardware requires either massive commitment or the failure of existing technology to...