56 IMPROVED FISHERY HARBOUR ACCOMMODATION 



" If, therefore, we find in front of a proposed harbour that 

 mttd reposes within a few fathoms of the surf ace, I believe we 

 have in that fact certain ground for concluding that our works 

 will never be assailed by a very heavy sea" 



MAXIMUM RECORDED HEIGHT OF WAVES IN LARGE 

 BODIES OF WATER. 



" At the harbour of Lybster, Caithness-shire, the waves 

 attained the height of 13^ ft. ; maximum length of fetch, 

 600 miles. At Sunderland the waves were found to be also 

 about 13 ft. high at the pier-head ; but the height was no 

 doubt reduced by the shallow water near the shore. Com- 

 mander Dayman observed that the highest waves off the 

 Cape of Good Hope were 20 ft, and Mr. Cockburn Curtis 

 says that the gales which produce these rollers extend to 

 from 300 to 600 miles. Mr. N. Douglas saw waves of the 

 height of 20 ft. off the Bishop's Rock Lighthouse. In the 

 Atlantic Ocean Dr. Scoresby, when at sea, measured the 

 waves with great care and accuracy on different occasions, 

 and the greatest height he observed was 43 ft. (Rep. Brit. 

 Assoc. 1850, p. 26)." 



LINE OF MAXIMUM EFFECTIVE EXPOSURE. 



" It does not follow, however, that the line of maximum 

 exposure is in every case the line of maximum effective force 

 of the waves, for this must depend not only on the length 

 of fetch, but also on the angle of incidence of the waves on 

 the walls of the harbour. What may be termed the line of 

 maximum effective exposure is that which, after being 

 corrected for obliquity of impact, produces the maximum 

 result, and can only be ascertained from the chart by 



