We have spoken of the driftwood boundaries of the Gulf Stream; but there is an even more pronounced barrier easily ascertained by a use of the thermometer. The warmest and most rapid part of the Gulf Stream is that in most immediate juxtaposition to a sheet of cold water flowing in an opposite direction off Carolina which bounds our river like a wall of ice. Occasionally the line of demarcation is so precise that it is visible to the naked eye, and the exact moment when a ship leaves the cold current and its prow cleaves the Gulf Stream may be observed. The latter waters are of a beautiful azure, that of the counter-current is greenish; one is saturated with salt, the other contains the mineral to a far slighter extent. But the chief distinction is that one is tepid, the other frigid as ice. On the 21st one of the men reported having sighted a light to the north, and had also clearly heard a distant bell tolling. This was probably the South Shoal Lightship, which marks the site of an ocean graveyard hereabouts. This lightship, with a crew of a dozen men, has been adrift nearly thirty times in the course of her history, and was once fourteen days in the Gulf Stream. She is a schooner or barge of two hundred and seventy-five tons, about one hundred feet long, chained to an anchor of three and a half tons. But it is said the life aboard is so unbearably monotonous to the crew that they cut the chain and so send the lightship adrift. The skipper was glad when the Gulf Stream carried him away from the neighbourhood, for he was reminded that over five hundred wrecks have taken place some leagues to the northward of his course. [Illustration: "THE TEMPERATURE OF THE STREAM WAS DISAGREEABLE TO HIM."] The _Miosen_ was now bound almost due east, as if headed for the Azores, for the great river curves at this point. Just south of Halifax, in longitude sixty-five degrees, they came across their first iceberg, drifting on the very edge of the stream. There is nothing so unhealthy for an iceberg as the Gulf Stream, and an iceberg seems to know it. When, however, it is fairly caught in its clutches it soon melts away to nothingness before it has been carried many leagues eastward, all depending, of course, upon its size. As with icebergs, so with whales, as we have already mentioned. The vessel encountered a whale later in longitude fifty, but it was obvious that the temperature of the Stream was disagreeable to him, for he soon headed again for the Arctic regions. Other whales make a dash through or remain by the side of the big river and so reach lower latitudes, but a brief sojourn is enough for them. The Gulf Stream is a river which can boast everything maritime but whales.