Nat the Naturalist

Nat's mother and father have died, and he is being brought up by an aunt and uncle, the latter being his mother's brother. His aunt does not care at all for boys, and in particular makes sniping remarks at Nat the whole time. But Nat's uncle is very fond of him, and they are great friends.
But enter the aunt's brother, a famous naturalist, back from some trip in South America. Nat, who has already shown great interest in collecting specimens from nature, is enthralled, helps him to stuff and catalogue his specimens, and eventually persuades him to take him (Nat) with him on his next trip.
This requires a little training in shooting and sailing. Then they are off, on a P&O liner sailing from Marseilles. On arriving in the Java Seas they disembark, purchase a little boat, and set off. Very soon they are joined by an enthusiastic native, and the trio spend some years collecting numerous splendid specimens, of birds, beetles, and anything else they can.
An unfriendly tribe of natives steal their boat, but does not find their hut and specimens. They set-to to build a boat of some sort, to get themselves away from such an unfriendly place. At the same time their native assistant disappears, presumably murdered by the unfriendly locals. What happens next we will not spoil the story by telling.