OrderOrder

Order

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.

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