The drawing below is from Gustave Eiffel's book describing the tower that bears his name. There are 53 of them in total.
IV. Foundation masonry (continued)
The 4th technical board is the continuation of the 3rd, it contains the plans of the masonry coming over the foundations. While the 3rd one is devoted to the views in height, this plate shows the views of section. We can clearly see the shape of the masonry. There are also details of chimneys, tunnels and other corridors.