The idea in fire-by-friction is thus to increase the heat-generating friction to a point where the heat created is sufficient to ignite the fuel (which in this case is combustible material in the form of wood dust).
(The idea in fire-by-friction; is; thus; to increase the heat-generating friction to a point) (the fuel; is; combustible material; L:in this case) (the heat; created; ) (the heat created; is; sufficient to ignite the fuel; L:a point) (the heat created; to ignite; the fuel (which in this case is combustible material in the form of wood dust)
The idea in fire-by-friction the fuel the heat the heat created the heat created
is is created is to ignite
thus to increase the heat-generating friction to a point
combustible material L:in this case
sufficient to ignite the fuel L:a point
the fuel (which in this case is combustible material in the form of wood dust