Jack Fortune and the search for the hidden valley

Enhanced descriptions from Syndetics:

An orphan child full of mischief, Jack lives with his crotchety widow aunt in eighteenth-century England. His naughtiness knows no limits, and when one day he goes a step too far, Aunt Constance decides that she's had enough: from now on, his bachelor uncle can take care of him. Uncle Edmund is in no way prepared for a boy with boundless energy and an impish streak - and anyway, he's off to the Himalayas to search for rare plants! But Aunt Constance is absolutely determined, and Jack's uncle has no choice - he will have to take the boy with him.

What follows is a terrific adventure that will see Jack and his uncle - the most unlikely of all expedition teams - sail to India, cross the jungle and reach their mountainous destination, before returning to London to present their findings to the Royal Society. Along the way, Jack will finally come to terms with the great loss that has blighted his childhood years and discover, quite unexpectedly, that he and his late father have much in common.