HARBOUR WORKS.

New Zealand Herald, Volume XLV, Issue 13869, 1 October 1908, Page 3

HARBOUR WORKS.

Sir,—As many persons have been misled as to ~: tho action of the Harbour Board, in reference , , ito the ; ferro-concrete construction: at tho Railway Wharf, I consider it;only just that another view of the situation should' be put before them. ' Ferro-concrete work "is" a most interesting study, as I understand : from \ th« opinion of several engineers, ,aud quite tlia reverse of the general idea of the public. - In the first place the steel requires to be placed in the concrete in a slightly rusty condition, i.e., the loose.rust or scale must be. brushed off, as it is necessary- for the forma- • ;. tioh of a chemical compound, which is solu-' lable silicate of iron. This is replaced by... [ another composition, which > surrounds thesteel, as I understand, forming an enamel;; : ,; which is insolulable, and'impervious to water,'and also improves with age; and as water, salt or fresh, has no effect on it, there is no reason why the work nroduced should nod-: endure for all time. Thero are a few do*, foots at the Railway hurl, where the steel enamel has not formed, and. oxidation ha 3 set in, but these faults admit of a common sense remedy. The Harbour Board's acting'" engineer reports .133 !piles,' and 117 braces .-.:.. showing rust, but the bulk of these are;bE! little concern. ' Some may be caused by, loose nails, ironstone pebbles, or when tho; -fides have been joined, and the rust marks'; allowed I.to remain. The. fact that watei? \ penetrates concrete, and gets to the steely is of little consequence, as water is absolutely necessary for forming a first-class enamel. If*' may be the cause of the" miss-fire, and oxida*.' tion has resulted,_ that there _ is insufficient material for chemical action j if the oonoreM * •■. too thinly covers the steel, as/some of tliat" defects; are out of the reach of the water. Five years ago some four piles were driven, off the Freezing Company's reclamation, and logs have knocked off some concrete. The bare enamel steel is visible, and yet remains * bright. When one contemplates the . greafl", structure of the Railway Wharf, tho few defects are a very small percentage. The" structure is supported by ,970 main piles, ■■;' some 60ft long, and there are about 70S sheet piles, 900 lengths of wallings, equalling ' about 11,100 ft in length, 420 diagonal braces', equalling 8400 ft in length, and' tho surfaea" : area of the wharf is j list about 62 acres, oil ' ;;v 283,000 square foot approximately, the: defec- ',■'■■■ tive area being about _ 375 x square ' feet.. Scientists are endeavouring .to discover ;«' remedy for pi-eventing tho formation o| ferric oxide (rust), and Dr. Oushman ha-}, formed _an opinion that dipping the steel ina solution, of bichromate acid will have th<( desired effect. I am only an embryo cn«. gincer, but this information J.have obtained! from others who have- studied the'subject and I was quite satisfied as to the stability of ferro-concrete structure when tho British Admiralty approved of if being ' uiecf-'aT CaU Hope Dock. I will give place to no one at to my great interest in this port and city " but - I do object to ;■ persons barking Vi shadows, and crying wolf when r there is na' wolf, to the detriment of our prosperous had ; September 25. , *"**-uk.

SHOP HOURS. • ' Sir.-Would any of your readers kind]* say why all the warehouses, wholesale hops mercantile offices, and factories "can do** down, at five o'clock in the evening; thus letting their employees- get tl« advantage of a bit of daylight and iAuio recreation before darbies* sets in, while th» retail drapers, grocers, etc., keep their places l of business open .till six o'clock, when," there is no one about uto , buy, ■ all tlio 4 " busiaess that is done in thai Inst' hour, C ' am sure, not paying for tho gas burned? Their hands get out at six; it is dark bf-> , fore they get home. Now, sir, will not soma ouowho has influence take this matter up*. . and, if only for tho find summer months, try, I and obtain this inestimable boon for the rc- | tail assistants', who, I know, .would ho pro- '■ 'pared to start at an earlier hour in. tlJ<*,' - i morning if necos-iary to obtain the; adyan-v-: r j fcage ■ of-an/extra-hour in tho'eventng."^*r~ : ,'OkK IjTTi!UJ3aTBI>.' •