Art. IV. — Shingle on the East Coasts of New Zealand. 

 By W. W. Culcheth, M. Inst. C.E., F.R. Met. Soc. 



[Read 8th May, 1884.] 



1. The following has been written from observations lately 

 made by the author in New Zealand. The conditions 

 attending the shifting of the materials which form the coast 

 in many places are of great interest to the engineer who has 

 to design protective works or harbours in such localities. 

 This paper deals more particularly with travelling shingle, 

 a subject that has given rise to much controversy. So long 

 ago as 1853 a paper on the Chesil Bank on the south coast 

 of England was read before the Institution of Civil Engi- 

 neers by Mr. (now Sir) John Coode, whose name is well 

 known in these colonies. The late Astronomer Ro}ral, Sir 

 George Airy, took part in the discussion on that paper, 

 differing in opinion on certain points from Sir John Coode. 

 This discussion was renewed at intervals, and so lately as 

 1875 an agreement on the points of difference had not been 

 arrived at. The opinion of those of the leading engineers 

 who were not prepared to support one side or the other in 

 these discussions, was that more information was required 

 from other localities, and that it was unsafe to generalise 

 from the results observed at the Chesil Bank. 



2. In this paper a few facts only will be stated, with some 

 deductions from them, the object being to direct attention to 

 the subject in this part of the world, in order that more 

 information may be collected and further light thrown on 

 the movements of shingle under varied conditions. Sir J. 

 Coode remarked in his paper of 1853 : — " There are few sub- 

 jects of greater professional interest than the accumulation 

 and travel of shingle, since the very existence of many har- 

 bours depends, in a great degree, upon a correct understanding 

 and judicious application of the laws which govern its 

 movement ; and without a knowledge of these it is impos- 

 sible to devise such measures as may with confidence be 

 adopted, either to assist its progress, direct its course, or to 

 remove accumulations that may have taken place."* Shingle 



* See Proceedings of the Institution of Civil Engineers, vol. xii., p. 520. 



