A HARBOUR DREDGING SCHEME

Otago Daily Times, Issue 11093, 21 April 1898, Page 6

A HARBOUR DREDGING SCHEME

7-.. t© yrKEy.BDi-f OH. I

- Sik,—Afc; the request of the members of tb6 Ot-igoVHarbour Board "of. the -7 5th:bf iMarch; 1898, the writer furnished a sketchplau showlug how thfey channel;could be dredged wifch'V combinationy of y bucket and 'centrifugal pijnip ; also 'an estimate for converting*the"dredje Vulcan, to suit'samei ;7.:.Thin wag referred to ytwo mechanical experts,:one, from Melbourne and the other belonging to Dunedin, who pronounced it unsuitable for the harbour. '"' I -Waa not snrpri»e'd at the finding, seeing that, one of thi] experts - iva« biaistd to suction', dredging, but if the board had fciieu adopted the scheme thousand* of poundi Would have'been saved to impßrteri,:who have had practically since thin to pay.double harbour rates: Of the'sucetisof the scheme there would not be the shadow of a doubt. : The rea»on of my writing'■ now is in consequeiice of Mr Barclay bringing forward the subject at last meeting of the board «» his, when it must ha»e come under his notice two yeara previonsly, and he might have had the courtesy to acknowleSgp the source from whence he gathered his* information. The following 'iß*. a oopy of my lefctar fee the Harbour Board. Their reply thereto was that it was. Unsuitable for Otago Harbour, j The scheme should'never have been referred to Mr Higgins, as hit was bound to be a bia«s«d opinion; it bsiiag a- rival scheme to his own.: Alao, might I ask; why Work to the value of hundred* of pounds' is given out without balling for tenders f orsame ?— rttmvi&c, '7y-' •".''•'■■• ::^HCMAs;'STEVisNSok. '

'777' 7--y- ,-'' ';Dun'edin;d;sth-March, 1896 Chairman, Otago.Harbour Board,'Dunedin.;';'

oeutlemen, —la compliance:- with- your request ofrthe'3rd Inst.v.we have much pleaiurevin enclosing sketch plau cf proposedjuethod. which consists Of using either one, or both sides; er laddert £« formerly, arid employing a small centrifugal ptfni-i driven by a iep*ir*te engine, to flush the materia) asiepdiited by the buckets through, the pipj-s The power required-to drive one set of: buckets and also the centrifugal pump:vvould-he about j eo Uorse-pawer.indicated, and.witb this expenditure of power about. 180 yards, of materjal would be dredged per hour; or. if the two sets of buckets were employed, about.36o yards would be dredged per hour with about 170. indicated" horse-power There would be the same number of men required to work the dredge iv each case—being the same number as you have had*employed in"yonr recent trial with the sand pump. ,In a paper read by Mr Higgles, before the Victorian Institute of Kngipeers, oh the Yon Schmidt dredge, he give* the quantity of material deposited, as "oeine 30.00* cubic yards in 168 hours, and using ac'engine indicating 330 horse-power = to 185-yards of materia] per.; hour as beinc deposited and consuming 330 indicated home-power in accompHshins this. ■■- - A*?* c ,foll°winc-is ay.comparuioii■■ of the two methods .--Ist,. Yon Schmidt, or what is in use on Vulcan-, 31,000 cubic" feet, in 16S houra, equal to 185 yards per hour, and cinsußiins 330 indicated horse-power ; :l»t method- propssed by the writer, using one »et of buckets o!ilj; ISO cubic yards per hour, jwith an expenditure of. about 1(10 horsepower ; 2nd, .using both »e:,rei' buckets, i'6o yards per hour with an expenditure of abeut 170 indicated horse-power. , ; No. 1 'method would cest approximately in altering - the dredge' £380. -including- plans and supervision. No. 2 method ■ would cost about £1100 approximately, including i-pUns and supervision.; alio. No. lmethod.ccnlri be completed and ready for working in about a fortnight. " I im pe r feqtly,satisfied.that if ,your ; board Cao-ree its,wny te '.'adopt; this system the. trouble of a shfciiovv harbour:will soon be a tKingof the past, aud shall be satisfied to take payment for using this ihctiiod by results obtained. The writer- will 'be -glad-to give you an. interview; when any explanations can be given, as.Bo.much.can be done in a short time personally which might consume a lot of time by writing.—l am, yours respectfully,

_„y Thomas StsvKxsdx For N;Z. Engineering and Electrical Company.