132 EXPEDITION TO JAPAN. 



the Indian archijielago, but throughout the South Sea islands, as it is generally conceded that 

 the natives of the latter are of the same origin as the former. Analogous physical character- 

 istics, customs and languages would seem to prove this relationship. 



The Mississippi having taken on hoard the necessary supplies of fuel, left Singapore on the 

 29th of March. The ship proceeded through the middle channel, passing near a light-house 

 erected on the rock called "Pedra Branca." This course was taken with the view of running 

 up on the Cochin China and Hainan shores. It is not necessary to say much in regard to the 

 navigation of the China sea, since so much has already been published on the subject. It may, 

 however, be stated in general terms, that nearly the whole expanse of sea fronj Borneo and 

 Palawan across to Cochin China is rendered dangerous by numerous coral reefs, banks and 

 islands. Many of these banks and reefs are below the surface of the sea, and although the 

 hydrograpical surveys may have truthfully stated their depths when they were taken, and 

 reported a sufficiency of water for vessels to pass, it must not be forgotten that such is the 

 rapidity with which those little architects, the coral zoophites, build up these foundations of 

 future islands, that the work of a few years may materially change the character and dejjth 

 of the soundings. With such obstructions the China sea cannot be navigated without danger, 

 and especially in stormy weather. Notwithstanding, thousands of vessels go annually through 

 its various passages in safety, while a disaster occurs now and then only. 



The surface currents are influenced by the prevailing winds, but the tides, as in other parts 

 of the world, are governed by some mysterious laws which the wisdom of man has not yet 

 entirely fathomed. The vertical rise and fall of the tide upon the coast of Cochin China varies 

 from six to fourteen feet, and the periods and duration of the ebb and flood are by no means 

 regular. In latitude 12°, on the same shore, there is but one tide in the course of twenty-four 

 hours. It has been said that the tides in the tropics rise and fall very little. Although it is 

 granted that in high latitudes the perpendicular flow and ebb is generally greater than in low, 

 still there are many examples of considerable tides in the latter. At the head of the Gulf of 

 Cambay, in latitude 22°, Horsburgh states that the perpendicular depth of the rise and fall of 

 the tides is from thirty to thirty-six feet at the full and change of the moon. So also, according 

 to the same authority, in Surat road, it is from twenty to twenty-one feet, and from fifteen to 

 seventeen in Bombay harbor. Again, in the Gulf of Martaban, which is far within the tropics, 

 the rise and fall of the tide, at the full and change of the moon is twenty-three and twenty-four 

 feet, and off Kangoon bar about twenty or twenty-one feet. In Caspar straits, within 2J° of 

 the equator, there is occasionally, from local causes, a rise and fall of sixteen or seventeen feet 

 on the spring tide, but this is rare in places so near the equator. These instances, all from 

 Horsburgh, show that very considerable tides occur within the tropics. 



The observation of the Commodore in regard to the single tide in twenty-four hours, on the 

 shore of Cochin China, is paralleled by analogous instances, also reported by Horsburgh, who 

 remarks : " Although in most places the tide ebbs and flows twice in every twenty-four hours, 

 this is not universally the case within the tropics ; for among several of the eastern islands the 

 tide flows only once in twenty-four hours." In many places, far beyond the tropics, the tide 

 likewise flows only once in twenty-four hours, particularly on the southern coast of Van 

 Dieman's land ; but at Port Dalrymple, on the north coast, the tide flows twice in twenty-four 

 hours. The zodiacal lights glowed in brilliant radiations almost every morning and evening 

 during the time the Mississippi was in the equatorial latitudes ; and the chaplain, (Mr. Jones,) 



