26 



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 w^ere 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 w^hich 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 



