These early lamps had a long wick which required constant trimming
throughout the night for the light to burn bright and clear.
Clockwork Mechanism
Next came lights with a lens that revolved round a single lamp by
means of a clockwork mechanism run by weights to give the effect
of a flashing light. The weights were suspended down the tower shaft
and one of the keeper's most important jobs was to wind up this
mechanism. If the light stopped revolving it could cause as much
confusion as if it were out altogether.
Revolving Light
In 1865 the first revolving light was installed at Dog Island lighthouse.
The light used 16 small oil lamps, each with its own lens. It was
a forerunner of today's electronically driven revolving lenses.
The average lens on the early lights weighed several tons, requiring
a strong mechanism to keep the system of wheels or ball-bearings
moving. This restricted the size of the lantern, reducing the power
and speed of the light. In the late 1880s a new type of lantern
was invented to overcome these shortcomings. The new lights floated
on a bed of mercury rather than on metal rollers, allowing easier
and faster revolutions.
Kerosene Lights
In the 1900s, incandescent kerosene burners were introduced, providing
economy with a more brilliant light and no trimming at all. Most
of these kerosene-fuelled lamps lasted until around the 1950s, when
all the lighthouses were gradually converted to electricity.
Electrification and Automation
In the 1950s, all lighthouses in New Zealand were converted to electricity,
accelerating the move to automatic lights. A typical New Zealand
lighthouse has a lens that revolves around a 1000-watt bulb. Most
lenses are made up of a number of upper, central and lower sections
that magnify the bulb light into beams. The lights are automatically
switched on by a photoelectric daylight sensor, which sends 12 volts
of power to the lighthouse, either from the mains electricity system,
diesel generator or by solar power. Some 70 lights are now generated
by solar power.
Remote Monitoring
The main lights and beacons around New Zealand are monitored remotely
by Maritime New Zealand from its Wellington offices via an active
control system. This enables the lighthouse engineer to check any
faults via computer, and to troubleshoot most problems remotely.
The rotation gear, lamp and power supply all have standby units
that are automatically activated if there is a failure. Any faults
are automatically relayed to Maritime NZ.
Maintenance
Today, all classic lighthouses are kept maintained and inspected
on a six-monthly basis. Access to each lighthouse is kept clear,
the structure kept sound, weeds are removed and all vegetation which
could pose a fire hazard in the summer is cleared away. Some technical
maintenance is done on each light, mainly on things such as diesel
generators. The lightbulb on main lights needs to be changed every
six months.
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