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by guide banks, or aided by periodical dredging. This is a highly important branch of the subject, and one upon which lam unable, with the data now before me, to give a positive opinion. Looking at the fact that the flood and ebb currents are shown on the new survey to run in a direction parallel to that which I have selected as the best site for the channel, with a velocity of from two to three knots per hour, there are good grounds for believing that the channel, when once formed, would be maintained with but little aid other than the scour caused by the passage through it of the tidal and river currents. There are thus strong probabilities that training or guide banks of rubble-stone —the formation of which in consequence of their length would be attended with great expense —would not be required, although in this case, as in most others of a kindred nature, occasional dredging may be necessary at certain portions of the channel for the constant maintenance of the improved depth. Much light would be thrown on the probability of the channel necessitating the formation of training banks, or otherwise, if the nature of the material which forms the shoal were clearly ascertained. For if it should he shown that the material consists of mud or silt deposited by the combined action of the sea and river, there would be reason to apprehend that the currents would require concentration and training between guide banks such as I have referred to. On the other hand, if it should appear that the sea-bed consists of a natural " hard " or obstruction which the currents are unable to scour away, there would be sufficient grounds for proceeding with the work iipon the understanding that guide banks would not be necessary. Hence, before coming to a definite conclusion on this question, the site of the proposed channel should be carefully examined, and borings made at the points indicated and numbered on Drawing No. 1, carefully referring all results to an uniform level of low water of ordinary spring tides, noting the strata passed through down to, say, 22 feet below low water, and giving the results of each boring with a number corresponding with that figured on the plan. In any event, I do not apprehend that the materials which form the shoal are of a character which cannot be easily dredged, neither is there any doubt as to the practicability of keeping open the channel after it has once been formed, seeing that if necessary the currents may Retrained and directed within guide banks, and the scour aided by periodical dredging. The points upon which further information is required affect the extent of the works, their first cost, and the charges for maintenance, but not their practicability or permanence, relative to which I imagine there can be no doubt, although the cost may be such as to necessitate their postponement until the trade of the locality is sufficiently developed to warrant the outlay. The best and most economical dredge plant for the formation of the channel would be a powerful steam hopper dredger of the kind patented by Messrs. Simons and Co., of Eenfrew, one of which has, I understand, been supplied to the South Australian Government, and has for some time been in successful operation at Adelaide. Having regard to all the circumstances of the case, I should suggest the purchase of a similar dredger for the work at the Thames. This craft would dredge 1,000 tons of material into a hopper formed as a hold in the ship, and proceed to sea and deposit the cargo of spoil at a distance of from seven to ten miles from the proposed channel, just below the low-water mark of the western shore of the Frith. A vessel of this character would do the work of an ordinary dredger and the usually attendant hopper barges. Under normal conditions she would make one trip per diem, equal to the disposal of 1,000 tons of material out of the channel; but in the summer, when the weather and tide are favourable, she could occasionally make two trips per diem, equal to the disposal of 2,000 tons of dredgings. A craft of this size and power would execute the work with sufficient rapidity, unaided by other dredging plant. Her crew would consist of thirteen to fifteen men. She would draw 7 feet 6 inches light and 11 feet loaded, and would steam with a full load from six to seven miles per hour. Operations would be commenced at the upper or landward end, and the work extended seawards : this order of procedure offering certain advantages with regard to the navigation of the dredger, and being in other respects preferable at the Thames to the more ordinary practice of commencing at the seaward end and working backwards. I have preferred a straight channel to one having a bend, because, in the case of the former, two leading lights will be sufficient to guide a vessel by night through the entire length of the new cut, the track being buoyed for navigation during thick weather in the daytime. I have shown two lights: one at Opaui Point, and the other on the left bank of the river to the south-east of it. It would also be necessary to erect two further leading lights on the salient angle of the foreshore northward of Te Kopu, for the guidance of mariners when passing over that portion of the river landward of the inner end of the new cut. In conjunction with the formation of the proposed channel across the bar, it will bo requisite to dredge the small patch or shoal below Te Kopu to the extent indicated on Drawing No. 1. Estimates, I estimate the cost of the works as follows :— £ No. 1. Extension of Tararu Jetty, 600 feet in length ... ... ~. ... 17,750 No. 2. Extension of Te Kopu Jetty, 300 feet in length, with a viaduct approach 160 feet long ... ... ... ... ... ... ... 11,900 No. 3. Diversion of channel at the outfall of the Kauaeranga, to improve the approach to Shortland Wharf ... ... ... ... ... ... 2,250 No. 4. Formation of a channel across the bar or shoal at the entrance, having a depth of not less than 8 feet at low water of spring tides for a width of 220 feet, including the purchase and delivery of a suitable steam hopper dredger, as hereinbefore described ... ... ... "• ... ... 65,000 No. 5. Deepening the channel provided in last item, so as to give not less than 12 feet at low water of spring tides for a width of 200 feet, an additional sum of ... 37,000 The total cost of the 12 feet channel would thus be £102,000, including the purchase of the dredger. The above estimates provide for contingencies and all other charges. In the case of Items 1, 2 and 3, the sums have been arrived at by applying the rates furnished by the colony to the quantities