The biform hypoderm is not always obvious where in some leaves there is but one row of cells.
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Thus, the legend of the fetid palace and its biform occupant has survived intact for more than three thousand years.
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Even though it has the biform monster at its centre, this is not a labyrinth as mythical threat, but a labyrinth as mode of contemplation, and as metaphor for life itself.
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Until the automation the lighthouse was lit by incandescent gas obtained from vaporised paraffin oil converted into a bunsen gas for heating a mantle. Since that time a new biform ML300 synchronised bifilament 20-watt electric lamp has been used.
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126 That same year a supertyfon fog horn was installed with sounders arranged around the gallery. On 15 December 1992 the tower became fully automated;Nicholson, op. cit., p. 127 the lower half of the biform optic remains in use but following automation the top half was removed and put on display (it is currently in the National Maritime Museum Cornwall).
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Black Nore Lighthouse at Portishead, Somerset, England, was built in 1894. It is a Grade II listed building. The metal white-painted lighthouse was built by Trinity House to guide shipping in the Severn Estuary as it made its way in and out of Bristol Harbour. Before it was decommissioned on 27 September 2010 the lens, a fourth-order 250 mm biform lens, flashed twice every ten seconds.
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The large concrete structures immediately to the south of the lighthouse were to provide the keepers with fresh water. The light was electrified in 1927, when the optic was replaced by a biform (i.e. two-tier) third-order sextuple-flashing rotating catadioptric optic, designed and built by Chance Brothers; the light had a range of and displayed six quick flashes in 7.5 seconds. It was lit by two 3 kW filament lamps, one on each tier (the lower lamp was fitted to a turntable lamp changer, which automatically lit a standby lamp (either electric or acetylene) in the event of a bulb or power failure).
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Supplies were taken up the rock face by an aerial hoist: a wire rope strung between the island and an adjacent islet was rigged with a traveller, which enabled goods to be winched up from delivery boats below. Within the walls of the lighthouse the keepers tended a small vegetable garden, for which the soil was transported to the island. The light has a focal plane of 180 feet, and originally had an enormous biform hyperradial optic high and weighing more than 8 tons. It was built by Chance Brothers & Co of Birmingham and, said at the time, to be ″ .... in relation both to size and character .... the most remarkable works of their kind hitherto achieved.
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Chance Brothers Glass Company made their first hyper-radial lens in 1887 in the UK. These lenses were originally named biform, and later triform and quadriform lenses, by Wigham. Thomas Stevenson used the term hyperradiant lens, and later they were renamed the hyper-radial lens by James Kenward of the Chance Brothers Glass Company. The hyper-radial Fresnel lenses were the largest ever put into use and were installed in about two dozen major "landfall" beacons around the world. The recipients include Makapu'u Point lighthouse on Oahu Island in Hawaii, Cabo de São Vicente in Portugal, Manora Point in Karachi, Pakistan, the Bishop Rock off the coast of Cornwall (in the UK), Cabo de Santa Marta in Brazil, and Cape Race, Newfoundland.
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The optic was designed and built by Chance Brothers and was 'biform' (having two identical lamps and lens arrays, one mounted above the other). Each tier consisted of an eight-wick paraffin burner set within a revolving array of extra large hyperradiant Fresnel lenses (consisting, on each level, of five pairs of lens panels, displaying two white flashes every minute). In clear weather the lower tier alone was used, with its lamp on half power; in limited visibility (as judged by the clarity of the light visible from St Agnes's Lighthouse, away) both tiers were used with the lamps at full power. The heavy optic was turned by a small air engine placed in the pedestal; compressed air was provided from a set of tanks, located in the room below along with a pair of Davey 'Safety' Engines, which drove the compressors.
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