From Short Stories To Longer Works

By James Blish
"At Death's End," set in New York, describes the discovery of antiagathics without which interstellar flight would have been impossible.

"Bridge," set on Jupiter and Jupiter V, describes both the exploration of Jupiter and the discovery of anti-gravity without which also interstellar flight would have been impossible.

They Shall Have Stars novelizes these two stories with new material, set in Washington, describing the political machinations without which early interstellar flight would have been impossible. (See here.)

Thus, the tripartite novel is a substantial opening volume for a future history which has six further installments since Volume IV is itself a collected tetralogy.

By Poul Anderson
Tales Of The Flying Mountains, which is a complete future history, has a similar structure, having developed through two stages.

(i) Stories in Analog by "Winston P. Sanders"
"What'll You Give?" (April 1963)
"Industrial Revolution" (September 1963)
"Sunjammer" (April 1964)
"Say It With Flowers" (1965)

Two titles change; the order changes; three stories and other new passages are added. Thus:

(ii) Tales Of The Flying Mountains (1970) by Poul Anderson
"Nothing Succeeds Like Failure"
"The Rogue"
"Say It With Flowers"
"Ramble With A Gamblin' Man"
"Que Donn'rez Vous?"
"Sunjammer"
"Recruiting Nation"
+ Prologue, six Interludes and Epilogue.

Of the additions:

"Nothing Succeeds Like Failure" describes the discovery of gyrogravitics;
"Ramble With A Gamblin' Man" describes the first gyrogravitic propulsion of an asteroid;
"Recruiting Nation" describes the preparation of the interstellar vessel;
the other extra passages are a dialogue during the interstellar journey.

Thus, what began as four stories with a common background becomes a continuous sequence.