“The exciting world of the outer galaxies”
Though the artist’s name is absent from both the cover and copyright pages of Eric Frank Russell’s Men, Martians and Machines, the cover art is almost certainly by Paul Lehr.
The appearance and presentation of the human figures (only one figure in the foreground, with several vaguely defined figures in the background), the scene’s limited range of colors, and the visual “softness” – versus the crispness and detail inherent to the works of Emsh (Edmund Emshwiller) – is consistent with Lehr’s art.
Jay Score, from Astounding Science Fiction, May, 1941
Mechanistria, from Astounding Science Fiction, January, 1942
Symbiotica, from Astounding Science Fiction, October, 1943
Mesmerica (first publication)
“Even at the time when space ships were making regular voyages across the universe, the MARATHON was a remarkable craft. Powered by the Flettner system, its speed was so great that for the first time exploration of the outer galaxies was made possible.
MEN, MARTIANS AND MACHINES describes some of the great voyages made by the MARATHON. There was, for example, the planet which was solely inhabited by machines – survivors, perhaps, from a civilization in which the first machine-makers had perished. On another planet, the inhabitants had developed the power of hypnotism to a fantastic degree, so that the observer saw only what he was willed to see.”
References
Men, Martians and Machines, at Internet Speculative Fiction Database
Men, Martians and Machines, at Wikipedia