Page:Proceedings of the Royal Society of London Vol 4.djvu/48

Rh By analysing the movements of the tides as determined by the most simple considerations of the laws of fluid motion in open seas and in channels, and by explaining the circumstances of their convergence or divergence, their interference with each other, their retardation in shallow water, and their consequent tendency to sweep round the coasts and to approach them almost perpendicularly; and further, by discussing very carefully all the materials which nautical surveys and books of navigation could furnish him, Mr. Whewell was en- abled to construct a map, which not only represented the general circumstances of the tides of the coasts of Great Britain, but like- wise the movement of the great tidal wave, on the coasts of Europe, in the Atlantic Ocean, in the Indian seas, and on the coasts of New Zealand.

It was with a view to correct this first approximation to a map of cotidal lines that Mr. Whewell procured a very extensive series of observations to be made on the coasts of Great Britain and Ire- land at 547 stations of the Coast Guard for an entire fortnight in June, 1834. These observations were repeated in June, 1835, and were accompanied by simultaneous observations made by the great maritime powers of Europe and North America, at the request of the Government of this country, at various stations on their coasts. The immense mass of observations, thus furnished, were reduced, under Mr. Whewell's directions, at the expense of the Admiralty, and some of the results, which are extremely important and in- teresting, have been communicated by him to the Royal Society in two Memoirs in our Transactions for 1835 and 1836. The last of these Memoirs was accompanied by a second map of the cotidal lines of the coasts of Europe, accompanied also by indications, ef- fected by a peculiar notation, of the total range, in yards, of the tides at the different stations at which observations had been made. Many very remarkable conclusions with respect to the motion of the tide-wave have resulted from these observations; amongst others may be mentioned the rotatory motion of the tide-wave which enters the German Ocean between the Orkneys and Norway, sends a southerly detachment along the coasts of Great Britain, which is reflected from the projecting coast of Norfolk upon the north coast of Germany, and meets the main wave again on the coast of Denmark.

It is impossible in the course of a very brief abstract like the present to notice all Mr. Whewell's researches in detail His second great object was to compare the observed laws of the tides with the theory, or to propose such modifications of the forms of the theory as would reconcile it with the observations.

The interest which attaches to such investigations, which is so great during the progress of the structure which is to be raised upon them, ceases in many cases when the fabric is completed: a remark which is applicable to many of the most important re- searches and discoveries in philosophy, where we are accustomed to regard the last form only in which the theory is compared with the facts which are observed, and to forget or to neglect the series of