The drawing below is from Gustave Eiffel's book describing the tower that bears his name. There are 53 of them in total.
X. Lower spacer and large beams of the first floor
Plate 10 relates to the detailed description of the assembly of the spacers, the braces and the main beam of the 1st floor. There is a lot of technical scheme, but all that is pretty uninteresting, except for those who are very interested in mounting the tower. But you have to go far in detail to appreciate this board. What is more accessible to the general public is the detail of the beam that supports the first floor, quite detailed.
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