prize8-1, Exercise 1: Beacon, lighthouse, lightship and buoy

Model answer (check the details):

A beacon is a fire or fixed light, often on a hill or a simple tower, that marks a place. It is the oldest kind of aid and does not need a purpose-built structure.

A lighthouse is a tower built to carry a permanent light that can be seen from a long way off. It is used on headlands, on rocks and at harbour entrances, wherever a fixed, high and lasting mark is needed.

A lightship is a ship, anchored at a fixed position, that carries a light. It is used where a tower cannot be built, for instance on a sandbank or in deep water.

A buoy is a floating mark, anchored to the seabed, that shows a channel or a danger, and it may have a light, a bell or a whistle. It is used in channels and harbours, where the mark must be small and cheap and may need to be moved.

Care: the boundaries between the kinds are loose. Some old towers are called beacons, and some modern buoys carry lights as bright as small lighthouses.