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Lyttelton Times, Volume XI, Issue 661, 9 March 1859, Page 3

-• oTtnird and preferable line passes through Lee's "^fl-it and crosses the occupation road with only 16 IWet -embankment, rising 1 in 60, then enters iffi cutting. i» t<he wlde slo P l»S ground below %Mv, Cookson's, attaining the depth of 35 iCfeet at 35 feet above high water, in Mr. Cookson's /}'orchard, where the mouth of the tunnel would be, '.^and thence descending 1 in 200 into." Lyttelton. || Ten chains or thereabouts may be carried on a level ■^Kat the mouth, and the tranverse section of the ;|l ground being flat there is no difficulty in widening Ithe cutting whenever a siding is required to receive I agricultural produce, which might be sent to Lyt|telton at proper times under the charge of a breuks- ■ |man, without engine power. I \ Mr. Cookson's well, near the line, is sunk through ©various strata of clay to a gravel bed about level f&with the tunnel mouth; therefore it is probable a considerable supply of water might be conMveyed from the valley to Lyttelton when the works SWe completed. During their execution tliis water hj would run through the open cutting to the Heatht" -cote, and any water soaking into the tunnel might jjjbe discharged by a pyphon with an air vessel and ]i||purnp at the top. Such a system of drainage i^ {would be quite efficient at the moderate depth of '!>i?l6 feet at which the works from Lyttelton end Jjj^nrould be met. !^- With respect to the nature of the strata to be Mraversed by the proposed tunnel, I would draw the Attention of the Commissioners to the Port hills as |>fen extinct volcano; Charteris bay being the proJibablo centre of such volcano. The streams of Hxva flowing from a crater of 5000 or 6000 feet elevation, have run 6 miles south to the Kaituna valley, 'tgj6 miles north to the Heathcote, 6 miles east to VlGodley Head, and 8 miles west to Ahuriri. •ft The streams of lava at their outcrop are seen to i'temsistof from 5 to 30 or more feet of solid rock, •iflrarying from each other in colour and hardness, 4;»nd covered with from 1 to 10 feet of ashes and . i!icoria, which, by the enormous weight of the superincumbent strata, have been compressed into a rock , "«>f great solidiiy. *'$$ The lava has a slope of 1 in 4 or 5, dir tarnishing as it cooled to 1 in 10 towards the extremity of its course, where it sometimes finishes •Abruptly with a steep slope. Occasionally the tffjfreight of fluid lava has overpowered the retaining ■, ftank' of scoria, and has burst through so as to form l-h short lateral spur, leaving a corresponding de--2 Igficiency in the top of the main stream. Ijp The lower beds of lava (about Rhodes' and StodjV^arfc's) have little or no inclination, so that, as the i ifunnel only rises 35 feet above high water, the li*trata traversed may prove nearly horizontal for a distance. :- S; One vertical dyke of solid whitish stone of moderate hardness, cuts the line of the tunnel at an I.6blique angle, and I have seen some indications of rlt second intersecting dyke. The rocks on either ■fcide of these dykes do not appear disturbed, but ■finerely cleft asunder and injected with 15 feet of iffluid stone. £■- In some parts of the Port hills points or peaks of i ;^hard rock, varying in structure from the adjacent ! ''lava streams, have protruded; but there is no indication of this having occurred in the line of the tunnel. \ lam therefore of opinion that the sides of the |.tunnel would be of solid rock, resembling that cut Ithrough by the Railway passing Herculaneum, and jtthat the roof would generally be sufficient for a £ single line. But if any strata were found to be of too Ipoose or perishable a texture to stand, a flat seg||jnental arch could be turned, to shield the rocks from fifdisintftgration-by the action of the steam and air, Eand the rails from the danger of falling stones. ijM The consideration of the Lyttelton terminus hayIfring been left by the Commission to Mr. Dobson, I jjhave not taken any steps with regard to it, but ll'merely.add to my plan the contour lines of the Custom House reserve, which I took in 1857, by desire |gbf the Provincial Secretary. -^- With reference to the Railway jetty, it may be '^observed that although the soundings in that part of ||fchebay available for such jetty may be insufficient •fjor large ships of 800 or 1000 tons to lie at anchor, yjjthere is no difficulty in dredging to the requisite tftlepth several berths for large ships alongside. ;;% Such a dredger as is required for this work has ||been delivered at Melbourne for £3,500, exclusive i^of mud boats. |1 I am, Gentlemen, M* > Yours obediently, f W. B. BRAY. f; Avonhead,-4th March, 1859. y "■