therefore they set out together from that place , and as the fell winter of that year came down upon them out of the north they went warily eastward under the eaves of the mountains of shadow/ at length they came in their journeying to the pools of ivrin , and looked with grief on the defilement wrought there by the passage of glaurung the dragon ; but even as they gazed upon it they saw one going northward in haste , and he was a tall man , clad in black , and bearing a black sword .