Law of universal gravitation

The Law of universal gravitation provides Professor Hardwigg’s explanation for the underground sea’s tides: even beneath the Earth, he argues, the sea remains subject to the universal attraction governing all bodies. The claim makes the hidden world continuous with the familiar one, as the travelers reach the shore and observe the water rising in a rhythm compared with the Atlantic.

The Law Applied Underground

Professor Hardwigg rejects the suggestion that the influence of the sun and moon cannot be felt below ground. His reasoning begins from universal attraction: because all bodies are affected by it, the vast inland sea should not be exempt from the general rule of the universe. He presents the underground setting not as a realm beyond physical law but as one in which familiar forces still operate.

The Sea as Evidence

Hardwigg supports his argument with an observable pattern. Despite the great atmospheric pressure below ground, he says, the inland sea rises and falls with regularity comparable to the Atlantic. As he explains this, the travelers reach the sandy shore and see and hear waves breaking on the beach; the water is evidently rising. The scene thus places a theoretical claim beside an immediate observation, turning the shore into evidence for the law’s reach.

Narrative Significance

The law offers an interpretive bridge between the expedition’s extraordinary environment and ordinary natural science. The sea is underground, yet its movement is described through a rule presented as universal. The narrator’s initial respectful doubt gives way to the visible rising tide, while his exclamation identifies the moment as a flood. The passage sustains its explanation through both argument and sensory evidence, without treating the underground sea as exempt from the world’s governing principles.