Apron paving

The concrete paving surrounding the base of the lighthouse tower.


The bars which support the glazing of a lantern. They may also support the roof. Simply a framing member between the glazing bars in the lantern glazing. In its true meaning an astragal is a moulding that has a rounded profile. In lanterns this is almost never the case



A walk way around the outside of the lantern, used for maintenance and, when  lighthouses were manned, for observing ships. Principal parts are the balcony floor and the balcony balustrade. (Synonym: gallery deck).

Balcony floor

Floor of the balcony. Montague Island’s balcony floor is 1880 granite slab. 

Balcony balustrade 

A handrail together with its supports. The supports are called balusters. Simply a railing or wall on the outer perimeter of the balcony, to prevent people from falling off the balcony. Generally made of metal stanchions and rails – Montague Island’s is 1880 gunmetal railing. 

Balcony door 

Door in the lantern base to give access to the balcony. In AMSA lanterns two doors are sometimes fitted but only one is operational. (Synonym: parapet hatch, service room door). 


An alloy of copper and zinc, commonly used for corrosion-resistant fixings and plumbing fittings.


An alloy of copper and tin.


Cast iron

A mixture of iron and carbon with a relatively high carbon content and a low melting point, produced directly from a blast furnace.

Chance Bros

English manufacturer  of  optical  apparatus, lanterns, cast iron stairs, cast iron  towers,  and other lighthouse components. The Chance family established a glass-making business in Smethwick, England in 1824 and is often described as ‘near Birmingham’. The business was absorbed into the Pilkington group of companies in 1951 and now ceases to exist.


Pattern of flashes of light emitted by a lighthouse, designed to identify that particular lighthouse. 


A red malleable metal of low resistivity.


Entrance vestibule

Enclosed passage or room between the outer door and the interior of the building.

External catwalk

Landing around the external face of the tower complete with hand rail. Montague Island’s is 1880 Chance Bros. cast iron lattice.



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.


Intermediate floors

Levels found mid-way up a building.  Montague Island has two intermediate floors of iron plate. 

Internal catwalk 

Open landing inside the tower complete with handrail. Montague Island’s original internal catwalk was removed and replaced with sheet flooring supported on the original openwork cast iron brackets.


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.



The 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

The level in a lighthouse at which 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.

Lantern glazing

The 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. Montague Island  uses three tiers of flat trapezoidal glass.

Lantern roof

Roof of the lantern. Usually made of copper sheeting over a framework of rafters. Montague Island houses an 1880 Chance Bros. part spherical dome.


Assembly transparent optically refracting element of glass. The surface is usually spherical in form.
Light source

Electric bulbs and LEDs now illuminate most lighthouses.


The principal structure of a lightstation, generally made up of a lantern, balcony and tower.


A precinct containing a lighthouse structure and other related buildings, for example. Keepers Cottages, store room, signal house



Shorthand expression of the size of an optical apparatus or lantern. At the time the system of  orders was established, when kerosene burners  were used, longer range lights needed larger  burners, and larger burners needed lens assemblies of longer focal length to ensure a sharply defined beam. In turn the lantern rooms were required to be larger to house these lens assemblies. AMSA historic lantern rooms range from 1st to 4th order.



Part of the optical apparatus, consisting of a metal column or base standing on the balcony floor inside the lantern and supporting the lens assembly and light source. Some later Chance documentation, such as their tariffs 1908, also refer to the lantern base as a pedestal.



Structure to support the lantern at a sufficient height above the ground. The most common types are the masonry tower, timber-framed tower, cast iron tower, and lattice tower.