In forest fires on mountainsides an angle of inclination is one of the chief factors affecting rate of spread. The author made some experiments to study close relationship between inclination of a slope and a rate of fire spread.
He set a fire on dry wood wool, stuffed uniformly in a rectangular vessel ( 4 × 3 × 50<cm>^3) in various inclined situations. Angle of inclination of a slope has been varied in a wide range, ranging from + 60° to - 50°. Table 1. - 6. and Figure 2 are the results obtained. He studied also a rate of spread on incense sticks.
As an empirical formula to be fit in both of his experiments and some other tests which were carried by Dr. TATIBANA in 1941, he submitted a following equation :
v_θ = v_0C^θ
Here v_θ is a rate of spread in cm per second on a slope, inclined θ degree from a horizontal plane, on which v_0 is a rate of spread. C is a coefficient of a rate of spread which will be given to each fuel. The suffix θ is inclination of a slope, being measured by the degree.