"There is an extensive ocean current of cold water, which coming from the northern regions of the Pacific, or, perhaps, from the Arctic, flows along the coast of California. It arrives charged with, and in its progress, emits air, which appears in the form of fog when it comes in contact with a higher temperature of the American coast, as the Gulf-stream of the Atlantic exhales vapor when it meets, in any part of its progress, a lower temperature. This current has not been surveyed, and, therefore, its source, temperature, velocity, width, and course, have not been accurately ascertained.
"It is believed by Lieut. Maury, on what he considers sufficient evidence—and no higher authority can be cited—that this current comes from the coasts of China and Japan, flows northwardly to the peninsula of Kamptschatka, and, making a circuit to the eastward, strikes the American coast in about latitude 41° or 42°. It passes thence, southwardly, and finally loses itself in the tropics. * *
"As the summer advances in California, the moisture in the atmosphere and the earth, to a considerable depth, soon becomes exhausted; and the radiation of heat, from the extensive naked plains and hill-sides, is very great.
"The cold, dry currents of air from the north-east, after passing the Rocky Mountains and the Sierra Nevada, descend to the Pacific and absorb the moisture of the atmosphere to a great distance from the land. The cold air from the mountains, and that which accompanies the great ocean current from the north-west, thus become united, and vast banks of fog are generated, which, when driven by the wind, has a penetrating or cutting effect on the human skin, much more uncomfortable than would be felt in the humid atmosphere of the Atlantic at a much lower temperature.