From the text ... 'But forest fires are still difficult to suppress once they get out of control and spread over large areas. Their progress depends primarily on wind, temperature, humidity, and precipitation, on the abundance and character of the fuels, and on the topography and presence of natural fire breaks such as lakes or barren mountain tops. It is probably the case that many major fires are still 'controlled' more by the exhaustion of fuel or by a change in the weather than by the efforts of man and his machines.'