Swatow--which is one of the five ports that a few years ago were thrown open by treaties to foreign trade--is situated on the river Han,[31] which is navigable for vessels of a light draft for some distance. There is also a spacious harbor at its mouth, with sufficient water to float ships of large tonnage. The river has several branches, which intersect a populous and fertile region of country, throughout which are scattered villages and large cities, as well as walled towns. In fact, it is said that no district in China presents greater natural advantages for agriculture and commerce than that in the neighborhood of this port. Double Island--which is the residence of foreigners--is situated a little off the mouth of the river, being about a mile distant from the main land, and five miles from the native town of Swatow. The area of land upon this island is small, a brisk walker being able to accomplish its entire circuit in half an hour without inconvenience. Standing high out of the water, it has two conspicuous and verdant hills, situated, the one at the northern and the other at its southern extremity. These hills overlook the two entrances to the harbor, and upon one of them are still to be seen the ruins of a native fort which once guarded the chief passage. The settlement, which faces the harbor, is built in the valley between; and most of it is so situated under the lee of the high ground as to be sheltered from the worst effects of the terrible typhoons which occasionally visit this region. The climate is very salubrious, and the island is considered one of the most healthy places for Europeans on the coast. Situated quite out into the sea, the inhabitants enjoy the cooling influence of the southwest monsoon through the summer, at which time invalids visiting the place receive much benefit from the pure and bracing sea-air. In fact, we were informed that at one time there had been some talk of establishing upon the island a _sanatarium_ for invalids, and that the scheme was favored by one of the best medical men in Hong Kong. Notwithstanding the fine sea-air at this place, the heat of the summer, which is of long continuance, is very exhausting to all foreigners; and here--as everywhere else in Southern China--the more temperate October days are welcomed with pleasure. The very warm weather, however, does not commence quite as early in the season as it does at Canton and Whampoa; but as we were at the South until midsummer, we did not have the mercury below eighty degrees from April until the 8th of October, and for by far the greater portion of that time it was some degrees higher.