Description: scientific water toys steamer, early edge education toy, tin boat - length 14 cm, width 6 cm, height 4 cm (approx). Function: how does it do that - when the water in the coil boils, the steam expands. This pushes the water out of the tubes. The reaction pushes the boat forward. As the steam continues to expand, it encounters the section of tubing that used to be full of water. This tubing is cold, and the steam condenses back into water. This causes a vacuum to form, which pulls more water back into the tubes. You would expect that the water moving back into the tubing would cause the boat to go backwards. However, the water doesn't get very far before it hits the end of the tube (the two streams of water in the two tubes meet each other in the coil). Any motion caused by the water being sucked into the tubes is reversed by the water hitting the front of the tube (the coil) and pushing the boat forward again. As you saw when you put your finger near the tubes, this back and forth water motion is fairly rapid, and the comparatively heavy boat never actually moves backwards at all. These are made in india on hand-operated presses, from tin plated steel. Hand-painted. They make a wonderfully loud "putt-putt-putt" sound as the steam around a bathtub,swimming pool or pond. Please note: product batch being different so the colors & pattern may have a little difference from pics shown, these are fancy utility items. Kindly analyze & read description, size & measurement details before order.