The shapes were swimming about, evidently by their own volition.
astronomy
по собственной воле
Действовать или двигаться по собственной воле, а не под воздействием внешней силы.
A Honeymoon in Space
A Honeymoon in Space is a 1901 novel by George Griffith. It was originally serialized in abridged form in Pearson's Magazine in 1900 under the title Stories of Other Worlds. The scientific romance story depicts a tour of the Solar System, a type of story that was in vogue at the time.