A familiar crashing sound came from the edge of the kampung; a couple of fruit pigeons had landed on the branch of a nutmeg tree. The blue-white birds were larger than chickens, and though they were slightly more streamlined in their own plump way it still seemed extraordinary to Prabir that they could fly at all. One of them stretched its comically extensible mouth around a nutmeg fruit the size of a small apricot; the other looked on stupidly, cooing and clacking, before sidling away to search for food of its own.

Prabir had been planning to try out his idea for altitude measurement as soon as he was free of Madhusree, but on the way back from the beach he’d thought of some complications. For a start, he wasn’t confident that he could distinguish between the shore of a distant island and part of a cliff or an inland mountain, visible over the horizon because of its height. Maybe if he could persuade his father to let him borrow the binoculars he’d be able to tell the difference, but there was another, more serious problem. Refraction due to atmospheric temperature gradients — the same effect that made the sun appear swollen as it approached the horizon — would bend the light he was trying to use as one side of a Pythagorean triangle. Of course, someone had probably worked out a way to take this into account, and it wouldn’t be hard to track down the appropriate equations and program them into his notepad, but even if he could find all the temperature data he needed — from some regional meteorological model or weather satellite thermal image — he wouldn’t really understand what he was doing; he’d just be following instructions blindly.

Prabir suddenly recognised his name amongst the murmuring coming from the butterfly hut — spoken not by Madhusree, who could barely pronounce it, but by his father.