The stranger takes off his hat - it's my Uncle! He invites me to his workshop in the neighbouring village, where he explains everything.
He apologizes for the disguise, but he's doing secret work, studying the remains of the Martian flying machine for the government. He thinks the key to flight is the special metal plates the Martians use. But he doesn't know how they work.
He has to use a fake name. He chose "professor Cavor" as a pun: he loves caves, from the Latin "cavus" means "hollow", and "professor Cavor" is a hollow (fake) name. But he feels like his research is becoming hollow as well: he isn't making any progress. I wish I could help.