This is:

A pear-shaped planet, where on its movement, the gravity changes dozens, if not hundreds of times. There is a reasonable life, the bushes. The Earthman decided to make a world trip together with his new fellow intellectuals. I remember nothing more.
What a book? I want to reconsider, read in childhood

Hall of Clement. The Expedition "Traveling"
Other works of the author are recommended to be read.