Kenneth Bulmer 
Of Earth Foretold 

The Prophets of Earth slept crated in their thousands. They filled the ship’s bomb-bays, lying quietly waiting in their machine-gleaming metal sheaths. Each one was destined to cover a world.Each individual one lay there, quiescent in its capsule, awaiting the master command that would send it, after the one before and preceding the next in line in strict mathematical order, out over a new and unknown world to plunge down to its destined consummation.