WATER SUPPLY BY AN ARTESIAN WELL.

New Zealand Herald, Volume III, Issue 719, 5 March 1866, Page 5

WATER SUPPLY BY AN ARTESIAN WELL.

To tlis Editor of the Hew Zeaiand Herald. Sir, —The subject of a supply of water for the city I*3 again before tho public. It is proposed to resume boring operations on the premises of Messrs* Thornton, Smith, and Firth, to ascertain "whether & continuous supply can bo obtained. It was, I believe, during the last session of the Provincial Council that Mr. TVni. Buckland brought forward a motion to the effect that it was desirable that the sum of £500 bo placed on . tho Kstimateo» for the purpose of proving, by boring, whether an adequ.ito supply of water for tlio city could be obtained. Tho site proposed b3 T tliat-gentleman for the experiment was the Market Reserve, which is situ* ated about 100 yards west from the fool of "Wake-field-street. In this letter I shall endeavour to prove that a more suitable site for tho experiment csnnot possibly bo found within the limits of the city. It is, I presume, pretty well known that tlie strata in and about Auckland belong to the tertiary formation ; that in the tertiary series, beds of porous sand occur at various derations, and that the water from tho sea, owing to in later.il pressure, finds its way into the horizontal branches of that series ; so that wherever n succession of sand-beds occurs resting on and alternating with impervious strata, wo may also expect to find subterranean " sheets of salt water." These remarks, of course, apply to places situated near tho sen. The bore liolt-, which was pnt down on Messrs. Thornton and Oo.'s premises, attained a depth of 350 feet, and the water struck is not, according to the remarks mude by Mr. Hunter in the Councii vesterday, suitable for the use of the inhabitants cf the <ity, owing to its being salt or salty water and if the tame bore bo prosecuted to a greater depth, and a feeder of fresh water bo met n'itb, there will still remain u serious objection to its being used for household purposes, lor, the fresh water from below will receive the " salt water" from above, and become bo mixed up, that it will be totally unfit for the purposes for which it will have to be applied. The distance from the bore on the mill premises to the .sea tide is about 200 yards, mors or less, and if we take into consideration tho porous nature of 'lie sand hills near the beach, it will at I once bo evident to every one conversant with the subject, that the salt wafer vriil be continually on the increase from the sea lo Messrs. Thornton and Co.'s i well. The sumo objection cannot be applied to the market reserve ; it being situated at so great a distance from tho sea on both M'los, that there need be no fear of any salt water peicolating through the strata, and entering the well, as id the case at the mill. Such a place as the market reseivo would be selected both by English and continental geologists, for testing, by means of an 'artesian wells," the springs cf a district. It is a well known fact to those conversant with geology, thr.t, at or near tho bottom of valleys is the ruost likely place where continuous feeders of water are to be nn t with ; that by boring iu such places, the feeders from the hills on each side will be tapped, and flow into the bore at the foot of (he hills, or centre of the valley. Now, the reserve is situated on a valley, which is formed by three hills—tho first is the hill in tho direction of " Waliefield-street," the second in the direction of " Grey-street, 1 ' and the t drd towards *' Hobsonstreet?' that if tho experiment be tried on tho site proposed by Mr. Buckland, the chaneos of succcss arc infinitely greater on the si 'e of the reserve than the other. Another reason why it is a more suitable site is this it is situated in a central part of the town, so that the water obtained could be very easily distributed in every direction. I hope that some one better able than myself will take up the subject, i-.rid give their view-" with regard to what spot they think tho most suitable for the well to be put down, &c. With regard to wh t Mr. McLeod said in the Council on tho method of boring, I beg to remark that tho system which he advocates has been practised by the Chinese for a great number of years, it is undoubtedly the simplest method practised, here all rods connected to the boring tool in the ordinaryplan nro dispensed with, the borer being suspended bv a rope, which, whoa the tool is worked vertically up and down imparts by its " torsion " a circular motion to tlio tool. In this caso the tnol and the rope are surrounded by an iron cylinder, and the products of the excavation become collected in the circular spaco between the tool and the cylinder, by which means thry may be brought up to the surface of tho ground. With so simple a m icliine, different tools, of course, being ti ed for various strata, it may be I'eked, Why has this plan not superseded all others? >'ow where simplicity can be gained without corresponding disadvantages, it is well to employ it, but wh- re a manif-1 inferiority exists, to choose sbnpl city in opposition to complexity, for its own sako alone, is absurd. To this plan one serious drawback occurs, which is, that the bore hole is apt to become crooked, so that a great difficulty if not impossibility, would take place in sinking tho pipes or tubes necessary for proteoting the bole. Until this fault is rectified, tho system of boring by impact alono, assisted by the twisting uction of the rope, will never become very general. The ordinary plap. is to attach the borer, which diflbrs according to the nature of the work to be done, to iron rods screwed together iu lengths of from 10 to 20 foot; a circular motion boing given to tho borer by tho workmen, assisted when required by a vertical jumping motion, causes the boriugtool to comminute the rock, and work for itself a" holo iu the ground. Where the rock to be acted upon is of a very hard nature, it is absolutely necessary that there should be a sufficient column of rods in order to produce a percussive force, sufficiently great to enable tho tool to do its work well. Those who practise tho " Chinese system" arc sometimes three years in boring their wells to the depth necessary to reach tho springs tboy are intended to attain, o>'E WHO DAS BOTIEO AN Artkwian" WELX,.