A lighthouse is a type of navigational aid for ships sailing in coastal waters. It shines by night flashing a distinct signal which aids the ship in determining its location and in warning the ship away from rocky dangers. By day it becomes a landmark.
The 1st recognised lighthouse was built in 280BC called Pharos of Alexandria and was considered one of the 7 wonders of the world. The structure was 137 metres high made of thick stone with elaborate carvings and other ornamentation. Sitting at the top of the lighthouse was a cylinder shaped container where a wood fire lit the harbour by night and a mirror reflecting the sun by day. This system was said to be visible for up to 55 km. The lighthouse survived several invasions and many earthquakes until it was completely demolished in the 14th century by an earthquake.
NewZealand lighthouses arrived over 2000 yrs later and were not unlike the Pharos in that they were lanterns left burning in cottage windows. The 1st of these was at Pencarrow heads in Wellington. For 17yrs this system guided sailors in and out of the entrance until the ship Maria hit rocks and sank in 1851. After that planning began for a proper lighthouse. In 1859 a 10 metre high tower was built. The tower was made of iron shipped out in pieces from England then bolted together on site. Most early lighthouses were made from wood but few survived the desolate conditions they were exposed to. Stone was used where available. By the 1880's New Zealand was constructing their own iron towers.
The first lighthouses were fixed lights that didn't flash. They were fuelled by burning either Sperm oil ( from the sperm whale ) or Colza oil ( a highly refined extract from rape seed) on a wick.These were a very inefficient as they required continual maintance by the keepers so trimming of the wicks was a on going job as if not they tended to smoke badly and who wanted a light that was sooted up
Because the fixed lights were being confused by similar lights along the coast they were eventualy replaced by revolving the lense of the light itself,but not with out some difficulty as extreme acuracy was requiried to hold and maintain the focus of the lenses.It took many attempts by various people who came up with wonderous ways and means to improve the casting of a good accurate reliable beam of light across the sometimes stormy.misty fog bound sea's.
Lense's used in lighthouse were developed in 1788 by a French man going by the name of Augustin Fresnel .He in conjunction with the Scotish enginering family firm( Stevenson's) are credited with the early development of light and lense units that are or have been use world wide ever since. They were able to magnify the flame of a typical lamp by nearly three times. It resembled a huge cut glass beehive surrounding a single light source. The light was bent through the prisms at the top and bottom to create a narrow beam of light. A magnifying glass at the centre intensified the light even further making it visible for many miles.
The problem with these early lights was that they weighed several tons and needed a strong mechanism to keep the system gears, pinions, shafts,and bearings moving. This restricted the size of lanterns that could be used and reduced the power and rotating speed of the light. In 1880 a new system of floating the lights on a bath of mercury was introduced making the revolution of the light easier and faster. This system was continued in New Zealand until about the 1950's when the dangers of mercury on ones health was discovered.
The lamps were eventually fuelled by kerosene, this sytem used a pressurized vapourised kerosene that was burnt injunction with a mantle,much the same as a lamp that is sometimes used when camping. This was introduced as it was more economical and had a brighter light. These were by far the most successful lights and lasted until 1950 when lighthouses began their conversion to electricity. Electricity made it possible to have a electrical light source most lighthouses remained with the fixed light but still retained the revolving lense system. As the introduction of electricity decreased the need for lighthouse keepers the lights were progressively demanned, today there are now no longer resident keepers.The old revolving lense's were removed ( does anyone know where ??) to be replaced by high tech electronic light units that are fully automatic fitted with self changing high powered lamps illuminating when sensors detect a change in daylight intensity.
All lighthouses are identified by their designated light patterns and these are noted on charts with a series of abbreviations giving mariners the most important features of the light.
Some of the abbreviations are.
F......... Fixed light with a steady beam
Alt....... Alternating light showing 2 or more colours successively
Fl........ Flashing light showing series of brief flashes, darkness longer than light
Occ..... Occulting light opposite to F1 fixed light is broken by short periods of darkness.
FFl.......Fixed and flashing light has steady beam varied by flashes of greater brilliance.
Southland is serviced locally by four lighthouses:
Centre Island built 1878, 12 metre high wooden tower built of Kauri. This tower stands 81 metres above sea level. It has a white light that flashes every 15 seconds is visible for 19 nautical miles( 35 kilometres). Because of the dangerous rocks around Centre island the island has red sector lights which shine an arc over the area to be avoided and this can be seen for 28 km or 15 nautical miles.
Puysegur Point was first lit in 1879. This is only a 5 metre high tower but is 45 metres above sea level. Its light can be seen for 41 km, 22 nautical miles and has a white light that flashes every 12 seconds. In 1942 a prospector who didn't like the light shining on him burned the lighthouse to the ground. A concrete tower replaced this in 1943.
Waipapa lighthouse light that is now upstairs in the Southland museum was lit in 1884.This was housed in a wooden tower standing at a height of 13 metres 21 metres above sea level. It also has the distinctive white light which flashes 5 times every 20 seconds and can be seen for 11 km or 9 nautical miles. This lighthouse was built after the Tararua disaster. The lighthouse greatly reduced the number of strandings on the point.
Dog Island was the first of Southlands lighthouses built in 1865 on a low lying rocky island 5 miles south east of Bluff. It was designed by James Balfour a relation of Robert Louis Stevenson the Son of one of the familys of the famous Scottish lighthousedesigners and buiders. The original tower was built from stone quarried on the island. Because of the exposed conditions and the peaty soil the tower shook in the wind and in 1871 developed severe cracks and a slight lean. The tower was reinforced with timber and encircled with iron bands. But again in 1916 it become structurally unsound and was strengthened by using an outer casing of ferro concrete. This is how it is today. The lighthouse stands as the highest lighthouse in NZ standing at 37 metres high. It has a distinctive paint work of black and white stripes to improve its visibility.
The Dog Island light was the first revolving light in the country with the unusual feature 16 small lamps each with its own lens turning inside a single lantern. In 1925 individual lamps were replaced by a single lamp and rotating lens. The keepers job on the island prior to electricity was to climb the 147 steps each night pull back the curtains that had been drawn in the morning to prevent the lens magnifying the sun and causing a fire. Once curtains were drawn he would pump up the air bottles then light the lamp mantle with a match. He would then wind the weights that hung down below the light mechanisim,as the weight fell they would by the means of a governing system it would slowly turn the rotating light. This job would have to be repeated every 4 hours until dawn. The light would flash 3 times every 27 seconds. Today with automation the white light flashes once every 10 seconds.
Other tasks the lighthouse keeper was expected to carry out was the general maintenance of the lighthouse, cleaning of the glass and lens a never ending chore considering the constant sea spray, in the very early days trimming of and adjusting the wicks in the lamps. Daily weather reports were required to be taken as well ,recorded by observing the cloud formation, wind directions, reading the barometer, thermometer, rain gauge,state of the sea and noting any other weather conditions.It was also required that Earth quakes be reported as soon as practicable. The information was then coded and relayed by Radio telephone to Awarua Radio station( now longer in existance) that was situated approx half way between the Southern City of Invercargill and the Port town of Bluff . This weather information went a long way in to aiding in the forcast of of the sometimes very stormy weather that the southern coast of New Zealand is renowened for.