かせい
force of a fire; force of flames
Noun
薪まきが足たりず、はやくも火勢かせいが衰おとろえはじめた暖炉だんろ。
The fireplace, lacking firewood, flames already starting to lose their vigour.
暖炉だんろには薪まきが足たりず、早はやくも火勢かせいが衰おとろえ始はじめている。
Without enough wood on the fire, the flames are already beginning to die down.