EuroGraphics Study of Northern River. 1000-Piece Puzzle. Box size: 10" x 14" x 2.37". Finished Size: 19.25" x 26.5". Tom Thomson was largely self taught and did not seriously pursue becoming a painter until he was in his thirties. He was won of the Group of Seven, a well known group of Canadian artists in the early twentieth century. With the Study of Northern River, Thomson shows his ability to transform a sketch into a successful studio painting.