“Oui, monsieur.”

“They will look a bit like that, only they will be inside the legs. Then we shall continue to build the legs up to the height of the first huge platform, which will hold them all together. That will be at a height of one hunded eighty-two feet. And it will be necessary to put scaffolding under the middle of the platform while we build it, of course.” He paused. “It’s not easy to do all that, I assure you.”

“I understand, monsieur.”

“Then comes something rather special. I have to make sure that the platform is absolutely, and perfectly, level. How to do that, young Monsieur Gascon? Give it a shove?”

“I don’t know, monsieur.”

“Then I will tell you.” He pointed to one of the tower’s four great feet. “Under each foot is a system of pistons, operated by compressed water, which allows me to make minute and subtle adjustments to the height and angle of each leg in three dimensions. Surveyors will take the most careful measurements.” He gave a broad grin. “Then I’ll go up and check with a spirit level.”

“Oui, Monsieur Eiffel.”

“Any other questions?”

“I have one, monsieur.” Thomas pointed to the great cranes that hoisted the girders up into position. “Those cranes will go only so high. Nowhere near the height to which we’re building. When we get to the height of the cranes, what happens after that?”

“Bravo, young man! Excellent question.”

Thomas politely waited.

“You’ll see,” the great man said.

It was already growing dark as he crossed the Pont d’Iéna to the Right Bank. Ahead of him, on the slope overlooking the bridge, stood the strange, moorish-looking Trocadéro concert hall, built a decade ago for the last World’s Fair.

Thomas smiled to himself as he passed this exotic palace. Ten minutes later he was at his lodgings. But he didn’t go in. He was feeling hungry. If he walked for another five minutes up the rue de la Pompe to where it crossed Victor Hugo, there was a little bar where he could get a steak and some haricots verts. He’d earned it.

Still feeling rather cheerful, he trudged contentedly along. On his right he came to the railings of the Lycée Janson de Sailly, and this made him smile again.

All Paris knew the story of the grand new school that had recently opened on the rue de la Pompe. The rich lawyer whose name it bore had discovered his wife had a lover. His revenge had been sweet. He had disinherited her, and left his entire fortune, down to the last sou, to build a school—for boys only! Though the lycée had only just opened, it was already fashionable. Thomas wondered cheerfully what had become of the widow.