Sentence:  Then came the arrowy flight and form of the hurricane itself&mdash;its actual bulk&mdash;its imbodied power, pressing along through the forest in a gyratory progress, not fifty yards wide, never <WSD>distending</WSD> in width, yet capriciously winding from right to left and left to right<!--, in a zigzag direction, as if a playful spirit thus strove to mix with all the terrors of destruction the sportive mood of the most idle fancy-->. 
Meaning of the word marked with <WSD> tags:  To extend or expand, as from internal pressure; to swell