Well, it's not much of a mystery, I grant you, and certainly wouldn't require the little grey cells of Hercule or three pipes for Sherlock, but I couldn't resist the title. And the sight of two saucepans sitting on the pond surface, steaming away, is a little on the eccentric side, even for a gardener whom he fears is known for his eccentricities.
But the pond keepers amongst you will understand, as might those of a higher latitude used to fishing through ice holes. Not that that is what I've been up to, I hasten to add.
Yes, it's ice-melting time once again, not so much to let the air in, but more to let noxious gases out. And we've found that a low impact way of doing this is to fill old saucepans with boiling water and place them on the ice. While we don't have fish in the lily pond, newts and frogs overwinter there, along with many other forms of pond life, so the aim is to cause as little disturbance as possible.
But, as we've found this week with the temperature not rising above 0C, the job has taken longer each day, with multiple refills of boiling water required, as the ice progressively thickens. A thaw is forecast, fortunately, so hopefully it too many more days to go...
P.S. we strongly recommend tying string not only to the pan handles but also the lids! It's not a pleasant or terribly easy exercise recovering such items from the icy depths!