FOR GREAT BRITAIN AND IRELAND. 81 



of the outer basin, where having arrived at the second 

 centre of disturbance, it spreads laterally along the insides 

 of the quays. 



The undulative force is, however, not nearly yet subdued, 

 and takes from the point B another departure, although 

 with diminished strength. But the conditions are now 

 altered, for the waves have entered a close harbour, that is 

 to say, the undulation meets with opposition from walls on 

 both sides as it expands to the limits of the enclosure on 

 either side. A certain amount of hindrance to the reduction 

 of wave-height is of course unavoidable ; but as the distance 

 from the entrance increases, so does the force of the radia- 

 tion diminish, so that on approaching the point C at the 

 entrance of the inner harbour, the run is very much 

 lessened. 



At this point C we have the third centre of disturbance, 

 whence the undulation spreads as before in several directions, 

 but is now disarmed of its violence, so that boats or 

 vessels in the most violent weather can remain in safety 

 moored to the quays. 



PROPORTIONS OF THE DESIGN. 



As regards the proportions of this form, both the inner 

 and outer divisions of the harbour are of nearly equal dimen- 

 sions, and it will be at once observed that, measured by 

 circles, each basin contains two in the direction of the base 

 line, and one circle and a half on the line of the perpendicular. 

 The writer, where circumstances permit, would by no means 

 object to the addition of half a circle of additional lateral 

 space to the enclosed areas, as in Fig. 3, facing p. 82, but 

 there are a large number of localities where this could not 

 be done ; and he, on this account, thinks that these pro- 

 portions will often be found suitable. 



VOL. IX. E. 4. G 



