Cut kernels from cobs; set aside. Break cobs into thirds, and place in a medium saucepan. Add 3 cups water. Bring to a boil. Reduce to a simmer, and cook for 20 minutes to make a corn stock. Strain, discarding cobs; you should have about 2 cups.
Meanwhile, in a medium saucepan, cook bacon over medium heat until crisp, about 10 minutes. Use a slotted spoon to transfer to a small bowl; set aside. Pour off all but 1 tablespoon of the bacon fat. To the pan, add the onion, and cook until translucent, about 5 minutes.
Add the potato, corn kernels, 2 cups corn stock, milk, thyme, and 1 teaspoon salt. Bring to a simmer, and cook, partially covered, skimming foam as necessary, until potatoes are tender, about 10 minutes. Taste, and adjust for seasoning. Sprinkle with reserved bacon.