Thermometers are given in the grid. Each thermometer has a bulb (a large round end) in one cell and connects several other cells in a path, ending at the “top” of the thermometer. Shade in some cells of the grid such that within each thermometer the shaded cells are “filled in from the bulb to the top”; that is, there is no unshaded cell closer (along the path of the thermometer) to the bulb than any shaded cell.
Each number to the top and left of the grid reveals the number of shaded cells that must be located in that row or column.
(Rules and example from PGP IB)
History of the puzzle
Invented by Yosuke Imai (Japan). Probably first appeared on the Puzzler magazine.