The Taranaki Herald.

Taranaki Herald, Volume XLIII, Issue 9954, 15 March 1894, Page 2

The Taranaki Herald.

vo PUBLISHED DAILY THURSDAY, MARCH 15, 1894. o - It can scarcely be asserted with any degree of correctness that harbourmaking in New Zealand has not been a beneficial undertaking. The peculiar sharje of New Zealaud, with its two main islands and vast coast line, naturally renders more harbours necessary than would be the case if it formed merely a portion of a continent ; and consequently more harbours than Nature had created became actually necessary so that the produce of each district could be easily shipped away. This harbour making has taken place at New Plymonth, Timarn, Oamaru, Napier, and Gisborne, whilst Dunedin has expended a large sum of money to improve and i ncrease the limited and inferior liarbonr accommodation which Nature there afforded. Although the results, owing to various causes, have not been in every case as successful as might have been desired, the money spent on most of the works has been well expended ; in fact has been quite as well laid out as in natural harbours, where the authorities have not always used their funds wisely or economically. Then there are our rivers, which have proved very useful outlets from which the produce of the districts could be shipped. The question of artificial harbours versus river mouths has been a subject much discussed. When a river's mouth is navigable at all it is sure to invite commerce. Bar harbours will not deter hardy mariners. Wherever there is a river of any size there has always been a settlement ; first,- because the river is a ready road which keeps itself in repair; secondly, because the land in the valleys is generally fertile; and thirdly, because in every river basin traffic naturally drains down towards some convenient centre in the valley. Trade gathers from small beginnings and grows according to the natural wealth of the surrounding neighbourhood. We have an instance of this in the Wauganni river. It follows then that when improved means of transit come to be discussed, the question practically is how to give better accommodation to the towns that have grown up, and that often means bow to improve the entrance to rivers, and how to deepen them inside. But in these days of jetties and moles the qn«3tion also aris.-s whether it it better to follow the leadings of Nati re or improve upon them — whether it is not cheaper and simpler to make artificial harbours on the coast than to toil at improving a river bed. Then we come to the question as to how are the bars to be removed ironi tbe entrances of river 3. A good deal of deep and practical thought has been given to that subject. Sir John Coode and others have considered the matter, the result of thoir observations being something as follows :—: — There will be no bar when the river discharges itself into the comparatively still water of a well-sheltered harbour. The waves are the true depositors of the bar, the river is only an excavator. The submerged beach, which ifc»the bar, is formed by the perpetual wash of the waves surcharged with sand. The action of the waves upon the sand ceases in about three and a half fathoms of I water, and the barless harbor or river mouth can only be formed by protecting it to at least tbatdeptb. The sand actually carried along and deposited by the tide is as nothing compared with that heaped up by the wash of the waves, and the current of a river, if concentrated as by a funnel to a small orifice will always scour out more than it deposits, and will tend to perpetually deepen vbe orifice which must be the channel of entrance. The cost of the work required to construct a funnel shape entrance to a river would be far more expensive than building out a breakwater from some headland : and marine engineers" as a rule are more favorable to the latter mode of making artificial harbors, than constructing a funnel sbape entrance to rivers. However, there is another matter to which we would refer, and which affects natural as will as artificial harbors, and even rivers. The action of the waves or an undercurrent is apt to cause sand or shingle to atcumnlate in places where it is not wanted, and dredges have to be employed to excavate the silt, which is removed out to sea. Timaru has suffered very severely from the drift of shingle, and two dredges failed to cope with the difficulty. The Harbor Board accordingly ordered from England a very powerful dredge ; one of the most perfect of its kind ever built. It has at last arrived and we learn that a couple of months' work will clear Timaru harbour ; and that there will be no use for it for months afterwards. If this is the case, which we are assured it is, Timaru will be able to lend her dredge to other Harbour Boards. Would not, however, it be bettor for the Government to purchase this dredge 7 We understand that if dredge No. 401 was employed a month in our harbour here, it would be capable of clearing out the aand, so tbat we should not require it again for years. At Waitara it could be used to advantage for a. mouth ; and even at Wanganui its utilisation for deepening the river would be beneficial. If the dredge was owned by the Government, those engaged to work it would be able to handle the vossel better than new crows being continually shipped. The matter deserves attention, and we hope the Government will see thoir way to carry out our suggestion.