To study what an influence exerts the fuel density on advancing flame fronts of forest fires, the author tested some woody materials, i. e. wood wool, wood pulp and others, stuffed in a vessel in homogeneous continuity under a complete dry condition, measuring the following articles in a windtight laboratory ;
(1) velocity of advancing flames in a rectangular vessel (4×3×50<cm>^3), and (2) fire durations in a round vessel (φ 15cm, 4.5cm deep).
Of the former measurements, shown in Fig. 2, he supposed the following equation for between distribution density ρ and average fire advancing velocity r,
r = (k_1)/(logρ) + a
Here k_1 and a are constants.
Of the latter measurements, shown in Fig. 3, he fonnd a following equation for burning duration D at the centre in a vessel,
log D = k_2logρ + b
Here k_2 and b are constants.