Study For Northern River By Tom ThomsonEuroGraphics Study for Northern River by Tom Thomson 1000 Piece Puzzle. Box size: 10' x 14' x 2. 37'. Finished Puzzle 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 one of the Group of Seven, a well known group of Canadian artists from the early twentieth century. With Study of Northern River, Thomson shows his ability to transform a sketch into a