THE LIGHTING OF THE HARBOUR.

Otago Daily Times, Issue 13941, 28 June 1907, Page 2

THE LIGHTING OF THE HARBOUR.

REPORT BY THE ENGINEER. Tho Harbour Board's Engineer (Mr J. Blair Mason) submitted the following report to yesterday's meeting of tho board on tlio feasibility and probable cost of lighting tho harbour by electricity: The entrance and chaimols of the Ota go Harbour are marked by 34 lights, burning kerosene, of whioU nine are in the lower and 25 in' the upper harbour. These lights, witli the exception of Harrington Point, leading beacons Cowling Bay, and Quarantine Island lights, aro exhibited from piles or pilo beacons erected on the edges of the channol, and extend over a distance of 13 miles from Dunedm- wharves. The distance of the lower harbour lights from tho source of elcctrical supply, their widely separated positions on opposite sides of the deep water channel, boar in t)ic application of electric lighting as to tho initial cost of its installation, and also as to its immunity from interruption by fouling of the necessary cables or overhead lines and consequent iaiilure of the whole system or of the individual lights.

In the consideration of any fias'able scheme of electric lighting for the channels, it is therefore thought better, to treat tho upper harbour as distinct from the lower harbour.

In any installation for Otago Harbour, I am of opinion that submarine cables are inadmissible owing to the unavoidable risk of fouling from vessels anchoring and from dredging operations; consequently one is confined to tho overhead system. Here, again, difficulty will be experienced, insomuch as Iho mains must be eroded on tho banks, and the leads to the damps bo carried across and down to the piles upon which they are p!aced. These lends would interfere with the movements of small vessels and' yachts, and prove extremely liable to be carried away, with consequent failure of tho light and derangement .of the installation generally. ' The i scheme of lightin 0 upon which the following estimate is based provides for the installation of 30 16-candlo power lamps, fitted to port hand channel, piles and connected up in series with 100-volt liglrt shunt coils to a high tension main carried on polos bolted to piles driven into the bank, an average of two chains irom iho line of the channel piles. Connection with the share is provided for by high tension armoured 1 submarine cables, which would cross the channel opposite Kavensbourne, and there top the corporation high tension main, which, it is assumed, will extend to that borough. The water in the channel at this place maintains a natural depth of lift, and being froo from dredging operations, a danger rmo could bo marked oft and precautions taken to make the cables comparatively secure. ' The estimated coat of tho abovo (assuming that the corporation high tenpion main ia extended to Ravensbonrne) is £3021 lGs. Tho estimated annual cost of electricity supply, renewals, and repairs, amounts to £120, and, with interest. 011 capital cost added, to £270 per annum.

In order to light the upper harbour efficiently, ar.d cspecinlly the Victoria Chance', it would lie desirable to provide lighting on both side:! of the channel. This, however, would involve a duplication of the above scheme at somewhat larger cost, by reason of the greater depth of water that prevails 011 the starboard side of tho channel than 011 the port fide. This would bring the cost of a complete clectrica! installation up to .{GSOO, and would increase the charges to £SGO per annum. " I have already pointed out the liability to derangement of an electrical system oi lightiiiff under the conditions mid circumstances that here exist. In addition there is tho not infrequent collision of vessols with tho channnl piles, resulting in the pi)c3 being broken or carried invay—a contingency that would add greatly to the cost of maintaining the system in dependable efficiency. Mr Barclay: What is the present cost of lighting? T.lio .Secretary: Tho contract for tho Upper Harbour is £2M. Mr Watson: This mattor is too previous altogether. Mr Koss said lio understood that tho engineer was experimenting with some now lamp. Mr Mason said that by Ihcso ho had hopotf to reduco the cost of lighting very considerably—to about £50 a. year within tho next six months, One man would be able to attend tho whole lighting system, Tho report was laid on tho table.