452. The hydrometer indicates the rainy latitudes at sea.—There is another indication which this little instrument has afforded concerning the status of the sea, and which deserves notice. We are at first puzzled with the remarkably light water between 9° and 16° S., Fig. 1, and in Fig. 2 between 7° and 9° N., as well as in 19° N. But after a little examination, we are charmed with the discovery that the hydrometer points out the rainy regions at sea. Rodgers' observations on his homeward passage from San Francisco to Cape Horn furnish the data for the curves {Fig. 1) between 37° N. and 57° S. Now Plate VIII. shows that the equatorial calm belt lies south of the line where it is intersected by the homeward route from California. It also shows that when he crossed the "Doldrums" in the Atlantic, that belt was in north latitude about 7°-10°, and that when he was in 18°-20° N. (Fig. 2) he was then passing through the offings of what are called the "Leeward Islands" of the West Indies, and that these are rainy latitudes at sea—the first two being under the cloud ring, the last being near the land in the trade-wind region, and confirming the remark so often made concerning the influence of islands at sea upon vapour, clouds, and precipitation.
453. Astronomical view.—The most comprehensive view that we are permitted to take of cosmical or terrestrial arrangements and adaptations is at best narrow and contracted. Nevertheless, in studying the mechanism which Wisdom planned and the Great Architect of nature designed for the world, we sometimes fancy that we can discover a relation between the different parts of the wonderful machinery, and perceive some of the reasons and almost comprehend the design which Omnipotent Intelligence had in view when those relations were established. Such fancies, rightly indulged, are always refreshing, and the developments of the hydrometer which we have been studying point us to one of them. This fancied discovery is, that a sea of fresh water instead of salt would not afford the compensations that are required in the terrestrial economy, and we also fancy that we have almost discovered a relation between the orbit of the earth and the arrangement of land and water on its surface and their bearing upon climate. Our planet passes its perihelion during the. southern summer, when it is nearer the centre and source of light and heat by more than three millions of miles than it is at its winter solstice, so that, on the 1st of January, the total amount of heat received by the earth is about 115 more than it receives during a
