234 HARBOUR CONSTRUCTION. 



" A triple line of buoys, of a mile in length, each buoy 16 feet long 

 by 9 feet in diameter, so moored, would require 400 buoys, and if 

 moored with two anchors, as proposed, in a depth of eight fathoms, 

 and with a scope of chain each way equal to three times the depth 

 of water, each buoy would require 50 fathoms in length, or 20,000 

 fathoms of chain, and 800 anchors for each mile in extent. 



" The experience of the Trinity House shows that chains re- 

 quire to be shifted once in four years, and as the cost of a buoy 

 and chains would be about 250, the expense of materials alone, 

 without the labour of mooring, would be at the rate of 100,000 

 a mile. 



" Independently of the cost and want of durability, we are of opinion 

 that the buoys, even with the addition of the matting, would not 

 reduce the main undulation of the waves ; nor is it by any means 

 certain, with spaces between them equal to four times the diameter, 

 that they could reduce the surface sea to any great extent. The 

 buoys, too, if hollow, might in a dark night be perforated by an 

 enemy and sunk, or they might be cut adrift." 



The designs for floating breakwaters which have come under 

 my notice have been of so unpractical a character that it would 

 serve no useful purpose to describe them ; but even supposing a 

 structure of this kind to be practicable, a most serious objection 

 to its adoption would be the extreme risk to which vessels lying 

 under its lee would be subjected in the event of its breaking 

 adrift during a heavy on-shore gale by no means a remote 

 contingency. 



Notwithstanding the extra precautions which are taken 

 in mooring lightships, of say 150 to 180 tons, at sea, it is 

 no uncommon occurrence for them to drag their moorings, 

 although they often find it necessary to veer to 180 fathoms of 

 cable. 



In the evidence given before the committee appointed by 

 the Board of Trade to inquire into the desirability of establishing 

 electrical communication between light- vessels and the shore, 

 it transpired that one great difficulty in connection with this 

 was the swinging of the vessel, which occasioned kinks and 

 twists in the electric cable. 



The chairman, examining Sir James N. Douglass, late 

 engineer-in-chief to the Trinity House, asked, " Am I right in 

 supposing (I have heard it said by persons, possibly not qualified 

 to judge) that, in order not to allow a cable to kink in any way, 



