3866.] 



Mr. T. G. Bunt on Tide-Observations. 



289 



December 6, 1866. 



Lieut. -General SABINE, President, in the Chair. 



The President announced that he had appointed the following Memhers 

 of the Council to be Vice-Presidents : — 

 The Treasurer, 

 Mr. Bowman, 

 Mr. Spottiswoode, 



Vice- Chancellor Sir W. Page Wood. 



The following communications were read : — 



I. " Discussion of Tide-Observations at Bristol.^^ By T. G. Buxnt, 

 Esq. Communicated by the Astronomer Royal, lleceived October 

 24, 1866. 



(Abstract.) 



This Paper contains the results of a Discussion of about 19,000 obser- 

 vations of Times and Heights of High "Water at Bristol, for the purpose of 

 obtaining the Empirical Laws of the Diurnal Inequalities of the Times and 

 Heights, and of the Solar Inequality of the Times, of the tides at that port. 

 Curves on Diagrams which accompany the Paper exhibit the results. 



The Observations were taken by a Self-registering Tide- Gauge, the 

 Clock of which has from the first been regulated by transit observation. 



The Diurnal Inequahties of the tides at Bristol are not large, that of 

 time averaging only 2 minutes (earlier or later), and that of height 2| 

 inches (greater or less). 



Although it was stated by Sir JohnW. Lubbock (in 1 839) that the diurnal 

 inequality in time is too minute to be observed on our coasts, the slightest 

 examination of the Diagram (No. 4) will be sufficient to show that 

 this remark is inapplicable to Bristol. On this diagram are laid down 

 the times and heights of tide registered there during six months of the 

 year 1865. In consequence of the tranquil state of the w^cather, the 

 agreement of the observed with the predicted times was unusually close ; 

 the average error in time, during the six months, being only 2| minutes, 

 and for six weeks less than 1*9 minute. The diurnal inequality, of time 

 as well as of height, is throughout the diagram most conspicuous ; and 

 the agreement of the calculated with the observed inequality close and 

 satisfactory. 



For each of the Diurnal Inequalities, the residues, or errors, of the cal- 

 culated Times and Heights were arranged for every half month, and for 

 each of the twenty-four hours of Lunar transit, making (24 x 24==) 5/6 

 Groups. The averages of these, laid down in Curves, are shown in Dia- 

 grams No. 1 and 2. 



Diagram No 3 shows the Solar Inequality of Time, obtained in a similar 



VOL. XV. 2 B 



