George O. Smith's Venus Equilateral stories from 1942–1945 are wonderful—if you like the idea of vacuum tube technology taken to extreme lengths.

Lots of fun in those stories for engineers and hackers: spaceships that can accelerate at six gees but the passengers can't, capacitors charged up in the gigajoule range, walk-in electron guns (why bother with vacuum pumps when you're in space and can just build devices in the "open air"?), stock market manipulation by means of speed-of-light delay, and SLAs.