﻿120 The Rev. T. K. Abbott on the Theory of the Tides. 

 This corresponds to a total accelerating force equal to 



FT cos ~bt; 



A, 



a result which agrees with that of Professor Stokes's more com- 

 plete investigation, with the exception of a slight difference of 

 notation. 



Terling Place, Witham, 

 December 30, 1870. 



[To be continued.] 



XVI. Addendum to a Paper on the Theory of the Tides. By the 

 Rev. T. K. Abbott, Fellow and Tutor of Trinity College, Dublin*. 



TN a former Number of this Magazine (Jan. 1870) I gave ele- 

 mentary proofs of the principal theorems in the Theory of 

 the Tides. In order to complete the elementary treatment of the 

 subject, it is desirable to give simple constructions for the disturb- 

 ing force, the velocity of the current, and the height of the tide. 

 The two latter I propose to give in the present paper ; it would 

 be superfluous to occupy your space with the former. 



It is in fact readily shown by elementary geometry that in 

 the figure f, where E B E'' represents the hemisphere under the 



moon, and a circle Oc'c B/is described round the radius directed 

 to the moon, the tangential disturbing force at a is proportional to 

 the perpendicular c p. If a a 1 be the space passed over in the 



* Communicated by the Author. 



f By inadvertence the direction of the motion in this figure is the reverse 

 of that in the figure in the former paper. 



