Abstract: Liquid used in a liquid-heating machine such as a turbine condenser is continuously circulated in an endless fluid flow path which passes through the machine and which is subdivided at a location spaced from the machine into a pair of parallel branches. A closed dry-type heat exchanger is provided in one branch and a wet-type evaporative cooler is provided in the other branch. A fan or the like is operated to form a pair of parallel streams of air one of which is passed over the closed heat exchanger for cooling the liquid purely by conduction, and the other stream is passed directly over the liquid in the evaporative cooler so as to cool it largely evaporatively. The heated air coming off the dry-type heat exchanger is mixed with the heated humid air coming off the wet-type evaporative cooler and liberated to the atmosphere.