Skylark of Valeron

Smith's most famous work is his Lensman series, but his first publication was The Skylark of Space. Smith went on to write a four-book series which is a defining work in the history of science fiction. Unfortunately it has not aged well and I do not recommend it.

Skylark of Valeron - After destroying the Fenachrone, Seaton and Crane take the Skylark out into intergalactic space. There they meet the Pure Intellects, who threaten to destroy them. Seaton and Crane escape by rotating into the fourth dimension, but in doing so they end up lost, unable to find their way home to their galaxy, to say nothing of finding Earth itself. Meanwhile back at Earth, DuQuesne has usurped the government and set himself up as dictator. Seaton and Crane manage to make an alliance with the planet Valeron, and the Valeronians help them make the scientific breakthroughs necessary to find their way home.