Sentence:  I had no horse, and the deep and wheeling stream of the river, rendered turbid by the late tumult of which its channel had been the scene, and seeming yet more so under the doubtful influence of an imperfect moonlight, had no inviting influence for a pedestrian by no means accustomed to wade rivers, and who had lately seen horsemen <WSD>weltering</WSD>, in this dangerous passage, up to the very saddle-laps. 
Meaning of the word marked with <WSD> tags:  To roll around; to wallow.