THE PACIFIC OCEAN, ITS ISLANDS AND ISLANDERS.
By J. E. Caldwell, M. D.
[Medical Missionary to the Islands of the Pacific.] WE often sing, "There is a wideness in God's mercy like the wideness of the sea," with only a slight appreciation of the meaning of the simile. Of the two hundred million of square miles on the surface of the earth, one hundred and fifty million of these are water. One-half of this surface, or seventy-five million square miles, comprise the Pacific Ocean. If you should mass together all the known continents and islands on the earth in the midst of the Pacific Ocean, you would still have an area of water surface equal to the Atlantic Ocean, and, perhaps, water enough, on account of its greater depth, to make an Indian Ocean besides. Notwithstanding the vast extent of this immense body of water, and though one might sail for weeks and months upon its billowy bosom in many directions without seeing land, it must not be supposed that the Pacific Ocean presents an unbroken surface of water. Nearly eight thousand islands have been described, with an area, exclusive of Australia (now generally rated as a continent), of one million six hundred thousand square miles, or more than one-half the area of the United States, excluding Alaska. These islands sustain a population of about seventy-five million people, equal to that of the United States and Mexico combined. Notwithstanding this large population and vast extent of territory, but little is known of these islands and islanders, even by intelligent, reading people. A great many people have crossed the Pacific in steamers which ply regularly from continent to continent, but, stopping only once or twice on the way at coaling stations, they learn but little of the thousands of islands they may pass, some of them only a few miles away. The greater number of these islands are of volcanic origin, though many are of coral formation. Most of them, especially in the tropics, even though of volcanic origin, are surrounded by coral reefs. In some instances these reefs surround single islands; again, immense reefs, many miles in extent, are found to surround whole groups of islands, furnishing the best of harbors for ships and boats of all kinds, in the very midst of the ocean. The reef around several islands of the Society group furnishes an example of this. Islands of volcanic origin are but the peaks of immense mountains that rise more or less abruptly from the bottom of the ocean, of unknown depth, some of them giving no anchorage763whatever for ships. Pitcairn Island, southeastward from the Paumoto group, may be named as a sample of this type. It is seventy-five miles from the nearest land, and more than three hundred miles from its nearest volcanic neighbors. Being but about one hundred miles outside the southern boundary of the torrid zone, it is an emerald gem in the midst of a wild waste of waters, but difficult to approach for want of good anchorage. The greater number of volcanic islands lie in groups. In its isolation Pitcairn is peculiar. The volcanic region of the Pacific is circular, or, rather, spiral, forming a chain, or belt, with the Sandwich Islands as the center, or starting point. Here is situated Kilauea, the largest active volcanic crater known. From here you may pass southward to the Society group, thence in a westerly direction through the Friendly Islands, from here farther west and northward through Japan, thence across eastward to the Aleutian Islands, and southward along the western coast of America, and you will not have left the region of the volcanic islands of the Pacific. Coral reef and islands are found in the Indian Ocean, also among the West Indies, and along the eastern coast of South America; but it remains for the Pacific to furnish the largest number of coral islands known to the world, as well as the widest distribution of reef-building coral polyps. The insect lives only in tropical waters. More than sixty feet beneath the surface he becomes inactive, and when one hundred and eighty feet deep he dies. In view of this fact, the existence of islands resting on coral foundations more than a thousand feet below the surface, was quite inexplicable for a long time. Finally, after it became known that some portions of the sea are constantly settling, while other portions are rising (this is known to be true of land surface as well as of ocean bed), Professor Darwin suggested that these deep coral formations must have begun long ago, when the foundations, now deep, were near the surface. Gradually these areas must have subsided, while, at about the same rate, the polyps built their rocky foundations higher and higher, until lofty mountains of coral were formed under the surface of the water. In this manner atolls must have been formed. Atolls are circular coral islands, the circles, or bands, sometimes broken on the side opposite the direction of the prevailing winds. In the production of an atoll the coral formation is begun as a fringing reef around an island. Gradually the island sinks lower and lower, the coral reef being built up at about the same rate. Finally the island is entirely submerged, and the reef is left a circular island with a lagoon in the center where the island formerly stood, always quiet as a mill pond, though outside the waves might dash and roar as they would. The Paumoto Islands (or Low Archipelago, as they are called to distinguish them from the higher, volcanic islands) are mostly of coral formation, abounding in atolls. They lie between the Society Islands and Pitcairn, above mentioned. Blue mud, largely formed of scoria from volcanoes and pieces of broken coral more or less ground up by the action of the waves, forms a great portion of the bed of the Pacific Ocean. The deepest sounding ever made, in which a specimen of the bottom was brought to the surface, was by H. M. S. Challenger, from the channel between the Caroline and Ladrone Islands. The bottom there was found to be volcanic. The depth was 4,475 fathoms, or a little more than five miles. The immense weight of water gave a pressure of five tons to the square inch, while the temperature at that depth was 33.9° Fahr. The Tuscarora, a United States ship, while making soundings off the mouth of Okhotsk Sea, found bottom at 4,600 fathoms, or about five and one-fourth miles. The above figures justify the following language, found in the "Encyclopedia Britannica:" "For a long time the opinion that the Pacific was a comparatively shallow ocean was entertained by geographers, and it is only the recent soundings of the Challenger, Tuscarora, Gazelle, and other surveying ships, that have succeeded in dispelling the illusion. It is now known that the average depth of the Pacific is greater than that of the Atlantic, and that areas of deeper water occur in it than in any other part of the globe."