I tell you, Tim – we shouldn't have let the professor go into that jungle! Three months have gone by and we have not heard from him as yet! 
History
The Roberts Plantation is located in Florida and owned by Professor John Roberts. It is neighbor of the plantation of John Crafton.
In the summer of 1939, Professor Roberts had been missing for three months when his working partner Ken Masters and professor's teenage nephew Tim Roberts checked the plantation-owner's world globe for the hints. They found out the spot in Amazon Jungle where Roberts had explored into and were able to get the professor back home.[1][2] It's unsure, was Masters also living in the plantation at the time.