160 EEPOKT— 1881. 



Fourth Report of the Committee, consisting of Professor Sir William 

 Thomson, Dr. J. Merrifield, Professor Osborne Keynolds, 

 Captain Douglas GtAlton, Mr. J. N. Siioolkred {Secri'tary), Mr. 

 J. F. Deacon, a>id Mr. Eogers Field, appointed for the pitrpjose 

 of obtaining information respjecting the Phenomena of the 

 Stationary Tides in the English Channel and in the North Sea ; 

 and of repjresenting to the Government of Portugal and the 

 Governor of Madeira that, in the opinion of the British Associa- 

 tion, Tidal Observations at Madeira or other islands in the North 

 Atlantic Ocean ^voidd be very valuable, with a view to the ad~ 

 vancement of our knotvledge of the Tides in the Atlantic Ocean. 



YouK Committee consider that the special ^yorks for which they were 

 appointed have been carried out. 



In this, their final report, they beg to mention that the pamphlet-notice 

 of the tidal observations, named in last year's Report as having been pre- 

 pared for those Continental observers who rendered valuable assistance 

 to the Committee in obtaining a portion of the observations, has been 

 circulated. 



It appears to be considered to contain valuable information, and as 

 forming the basis, or starting point for common action in the future ; 

 when the subject of the phenomena of these stationary tides receives the 

 attention it deserves, and whenever it may appear desirable to study the 

 entire question in a close and thorough manner. 



No ofl&cial reply has been received by the Committee (indeed it was 

 hardly to bo exjaected) in answer to the inquiries made by it respecting an 

 international datum for tidal observations, and as to future concerted 

 action amongst the various maritime Governments respecting a more 

 extended series of tidal observations. 



Nevertheless, the advantage of a common international datum, which 

 has for some time been desired, seems to be acknowledged ; and though 

 the datum suggested by the Committee has in no way been recognised as 

 such, yet no objections of any moment have been raised against it ; wliile 

 considerable value seems to be attached to it, as having at least done much 

 to advance the desired object, if not to offer the actual solution which is 

 most desirable. 



With regard to the second object of the Committee : — to urge tho 

 desirability of the Azores Islands as a station, where a series of valuable 

 observations might be carried out upon the tides of the North Atlantic 

 Ocean, it has already been stated that the Portuguese Government 

 readily took up the idea, and had established a self- registering tide-gauge 

 in the Bay of Funchal. 



Another incidental duty which fell to the lot of the Committee was to 

 urge upon the Board of Trade the importance of a self-registering tide- 

 gauge at Dover. 



That department of the Government, as already reported, set up at its 

 own expense the desired instrument, which is working regularly and 

 giving satisfaction ; so that, before long, a series of permanent records 

 may be expected from this most important station, which will serve aa 

 data for future observations, when required. 



