Page:Physical Geography of the Sea and its Meteorology.djvu/20

xiv The results that are embodied in Plate I. alone of this edition would, had the data for it been collected by a force specially employed for the purpose, have demanded constant occupation from a fleet of ten sail for more than one hundred years. The coordinating of these observations after they were made, and the bringing of them to the present condensed form, has involved a vast amount of additional labour. Officers here have been engaged upon the work for many years. This patient industry has been rewarded with the discovery of laws and the development of truths of great value in navigation and very precious to science.

It would be presumptuous to claim freedom from error for a work like this: true progress consists in the discovery of error as well as of truth. But I may be pardoned for saying that the present edition of this work will be found to contain more of truth and less of error than any of its predecessors, simply because it is founded on wider research, and based on the results of more abundant observations than they. Indeed, it could not, or, rather, it should not be otherwise; for, as long as we are making progress in any field of physical research, so long must the results continue to increase in value; and just so long must what at first was conjecture grow and gain as truth, or fade and fall as error.

The fact seems now to be clearly established that the atmosphere is very unequally divided on opposite sides of the equator, and that there is a mild climate in the unknown regions of the antarctic circle. Over the extra-tropical regions of our planet, the atmosphere on the polar side of 40° N. and 40° S. is so unequally divided as to produce an average pressure, according to the parallel, of from 10 to 50 lbs. less upon the square foot of sea surface in southern than upon the square foot of sea surface in northern latitudes. These, and many other developments not

Mr. Trembley to conclude that there are, "at the bottom of the water, mountains, plains, valleys, and caverns, just as upon the land."

But by far the most interesting and valuable book touching the physical geography of the Mediterranean is Admiral Smyth's last work, entitled ". By Rear-Admiral.," &c. London: John W. Parker and Son. 1854.