At first glance Visitors to the Inner Earth by Professor Solomon looks a bit like one of Terry Deary’s Horrible Histories. The photo of the author on the back cover, preparing to enter a cave and wearing a tool vest, hard hat and dapper shirt and tie as well as the light-hearted cover illustration, all help maintain the impression that this is a tongue-in-cheek visit with some of those who claim to have travelled deep into the earth and found remarkable things there.