The growth of knowledge about the free burning fire is observed to be of the slow evolutionary type of cut and try, as man has had to attack the unwanted fire through the centuries. Since such fires are the result of intimate interaction of geometry, chemistry, thermodynamics, fluid mechanics, and heat transfer, each at an advanced level, it has not been possible prior to the present century—almost the present decade—to use accumulated scientific know-how; there simply was too small an accumulation. This condition is changing and changing rapidly. In this paper some of the problems of the free burning fire are described, an indication of the present state of understanding is given, and some suggestions are made for these avenues of approach that appear hopeful of successful attack in the near future.
Specifically, fire spread over building materials, through buildings, and through forests, is described in sufficient detail to indicate where we are today, where we should be going, and what it might get us if we went. The innumerable detail problems which must be individually solved and combined to produce solutions to the larger problems are little more than hinted at in the discussion. But it is clear that many man-years of research, worth many millions of dollars, will be required to solve these problems, but with the cost of fire to society of many billions of dollars every year the indicated research is more than urgent.