The lighthouse signal

An original fiction passage set in the nineteenth century.

The keeper saw the light beyond the harbour wall. It appeared once, vanished, then returned farther to the east. He wiped the glass, suspecting a reflection from his own lamp. The light remained. Below, the sea was a black field with no path through it. He fetched the telescope and called his daughter to hold the lantern.

Through the lens, the light became three small flashes. Then darkness. He waited, counting under his breath. Three flashes again. His daughter asked whether it was a ship. He did not answer immediately. Instead, he took his coat from the peg and told her to ring the harbour bell. The question had become something that required action.

Analyse how the writer uses language and structure to build uncertainty about a light at sea. Support your answer with references to the passage.