Document ID: chunk:federal_register_of_legislation:F2022L01461:reg:2027:p3
Version: federal_register_of_legislation:F2022L01461
Segment Type: reg
Provision Reference: reg 2027 (pt 3/9)
Character Range: 126759–129475

of the light. In comparison, a helical bar design crosses the light source at an angle, obscuring part of it.

Glazing – middle section of the lantern, circular or polygonal in plan, between the lantern roof above and the lantern base below, made up of glass panes held in a framework of glazing bars and astragals.

I
Incandescent kerosene – a light fuel once utilised by lighthouses to ignite and fuel the lantern.

Intermediate floors – levels found mid-way up a building. Mersey Bluff has two intermediate floors comprised of slate slabs.

Iron – there were two common types of iron used in lighthouse construction; wrought and cast. Older lights will almost certainly contain these iron types. Wrought iron has been worked by hand and is an iron alloy with a very low carbon content in contrast to steel, it also has fibrous inclusions. Cast iron is iron which has been heated until it liquefies, and is then poured into a mould to solidify.

L
Lantern – glazed enclosure, usually of cylindrical or polygonal shape, at the top of a lighthouse, which surrounds and protects the optical apparatus. It contains the optical apparatus, made up of the lantern roof, lantern glazing and lantern base sections.
Lantern floor – level in a lighthouse where the lantern is installed, and by which access may be gained to the optical system and to the inside and outside of the lantern glazing. The lantern floor is generally at or near the same level as the catwalk and can be made from steel, concrete, or timber. Mersey Bluff's lantern floor is of slate slab.
Lantern glazing – middle section of the lantern, circular or polygonal in plan, between the lantern roof above and the lantern base below, made up of glass panes held in a framework of glazing bars. On the landward side there may be blank panels in place of glass, or other opaque construction. Types of lantern glazing include: flat and curved trapezoidal panes and curved diamond/triangular panes. Mersey Bluff's lantern glazing are comprised of flat rectangular panes.
Lantern roof – roof of the lantern. Usually made of copper sheeting over a framework of rafters. Mersey Bluff's lantern roof is a copper-sheeted part-spherical dome.
Lens assembly – a transparent optically refracting element of glass. The surface is usually spherical in form.
Light source – LEDs now illuminate most lighthouses.
Lighthouse – the principal structure of a lightstation, generally made up of a lantern, balcony and tower.
Lightstation – A precinct containing a lighthouse structure and other related buildings, for example. Keepers' cottages, store room, signal house.

O

Optical apparatus – equipment to provide, direct and control the light emitted by the light source.