Some years ago, there arose a need to predict the thermal performance of cooling towers when used underground with refrigeration plant in the extensive, deep gold mines of South Africa. After numerous attempts to apply the design information given in Chapter 21, ASHRAE HANDBOOK & Product Directory, Equipment volume, 1972, to what is essentially a straightforward problem, it occurred to the author that this was perhaps a situation where den Hartog's law applied. This law may be stated as follows:

"If a long and complicated analysis leads to a simple answer to a problem, then there must be a more simple straightforward analysis that will lead to the same answer."

Subsequent research has revealed that there is indeed a simple, direct method for predicting the performance of cooling towers. Furthermore, the method needs no "empirical adjustments", as do the methods referred to in the standard references. The purpose of this paper is to explain this new method, and to request comments from specialists on cooling towers on the extent of its applicability.