RANGITOTO BEACON.

New Zealand Herald, Volume LXIX, Issue 21116, 25 February 1932, Page 13

RANGITOTO BEACON.

MODERN PLANT INSTALLED. INGENIOUS EQUIPMENT. CONFUSION OF CITY LIGHTS. Ships approaching tho port of Auckland by night by way of the Rangitoto Channel depend on the light from the Rangitoto Beacon to guide them from the wide waters of tho Hauraki Gulf to the narrower entrance of the channel, and while this light has served efficiently sinco 1905 it has been necessary in recent years to alter tho method of lighting from gas to electricity and to greatly increase the power of tho lantern. This need has been brought about by the multiplicity of bright lights and electric signs which pow dot tho foreshore of the city and suburbs, making it difficult for visiting shipmasters to pick out the beacon with any degree of certainty. In keeping with the outstanding efficiency of the port the work of transforming the beacon has been done in a typically competent way, the whole of the plant and appliances having been designed and erected by the engineering staff of tho Auckland Harbour Board. The method by which the beacon has been modernised was explained to members of the board by the engineer, Air. D. Holderness, during an official visit of inspection of the various harbour works made by the members yesterday. The beacon was erected in 1887 as a daylight beacon only, but in 1905 a white flashing Pintsch gas light was installed. This served until 1914, when the power of the light was increased by the installation of incandescent burners. However, in 1925, owing to the increasing difficulty experienced by shipping in picking up tho light, the colour was changed to red. The following year tho Pintsch gas plant was replaced by a dissolved acetylene apparatus. Tho necessity for still further increasing the light power led to the beacon being converted to electricity at the end of 1930 An Outstanding Light. It has become evident, however, that with the increasing intensity of lights on the city shore and skyline, the task of improving the power of the beacon would be a continuous process, and, on the recommendation of the engineer, the board decided to make the beacon the outstanding light at the port entrance. For this purpose a submarine cable 4000 yards in length has been laid across the ship channel from St. Leonards Road, Takapuna, to the beacon. The question of generating power at the beacon itself was considered, but the possibility of interruptions and the difficulty of approaching the beacon to effect repairs in heavy weather made it necessary to have the power supply on the mainland. In case of interruption to the main supply, however, a small petrolelectric generating set has been installed at St. Leonards Road, so arranged as to start up automatically the moment power fails. When power is restored in tho Power Board's mains the auxiliary plant automatically closes down. There are further emergency devices at the beacon itself. Two floodlight projectors, 14in. in diameter, each equipped with a standard 250-watt, 32-volt concentrated filament lamp, are mounted on a vertical shaft, which is revolved at a rate of 5 r.p.m. by a 1-6 h.p. motor, acting through specially-designed reduction gear. Each lamp is wired on a separate circuit, as it is necessary to use only one lamp at a time, tho other being an emergency light. The current to the top passes through a thermal relay, which, when sufficiently heated, opens the circuit to the bottom lamp. Should the filament of the top lamp burn out, the thermal relay cools off, thus closing the circuit to the bottom lamp, which lights up in place of the top lamp/ Four Times Previous Power. Each of these lamps has an equivalent of 1600 candle-power, which is about four times that of the previous light, and it is possible by a simple adjustment to increase even that power. Hie members of the board were impressed by the ingenuity shown by the staff in the carrying out of this installation. and the engineer was congratulated on the success of the work. It may be necessary in the near future to increase the power of the Bean Rock and Sandspit lights for the same reason that made the improvements to tho Rangitoto Beacon imperative, but this work will occasion no difficulty.