Steam and hot water from inside the earth have been used for energy since primitive times, when people learned to cook food in natural ""leaks."" In the early part of this century, steam from the earth was harnessed to produce electricity in Lardello, Italy. Today, there is a substantial dry-steam power plant at Lardello, and two more in California and Japan. Geothermal hot water is producing low-cost energy in New Zealand, Mexico, and Indonesia. Elsewhere, geothermal power is being put to ""101 uses,"" and experimental projects and exploration continue. Goldin explains where this energy comes from and how it is located and extracted, and she gives a narrative interest to the report by describing problems encountered and solutions devised at particular sites. With no consideration of energy policy, Goldin provides no basis for assessing the prospects she raises. However, as in last year's similarly positive Oceans of Energy, she pictures exciting possibilities. As she concludes, ""Of course, this is 'tomorrow talk,' but tomorrow will come whether anything constructive is done about these energy forms or not.