Page "Gustave Eiffel" Paragraph 39

Work on the foundations was complete by 30 June and the erection of the iron work was started.

Although no more than 250 men were employed on the site, a prodigious amount of exacting preparatory work was entailed: the drawing office produced 1, 700 general drawings and 3, 629 detail drawings of the 18, 038 different parts needed.

The task of drawing the components were complicated by the complex angles involved in the design and the degree of precision required: the position of rivet holes were specified to within 0. 1 mm ( 0. 04 in ) and angles worked out to one second of arc.

The components, some already riveted together into sub-assemblies, were first bolted together, the bolts being replaced by rivets as construction progressed.

No drilling or shaping was done on site: if any part did not fit it was sent back to the factory for alteration.

The four legs, each at an angle of 54 ° to the ground, were initially constructed as cantilevers, relying on the anchoring bolts in the masonry foundation blocks.

Eiffel had calculated that this would be satisfactory until they approached halfway to the first level: accordingly work was stopped for the purpose of erecting a wooden supporting scaffold.

This gave ammunition to his critics, and lurid headlines including " Eiffel Suicide!

" and " Gustave Eiffel has gone mad: he has been confined in an Asylum " appeared in the popular press.

At this stage a small " creeper " crane was installed in each leg, designed to move up the tower as construction progressed and making use of the guides for the elevators which were to be fitted in each leg.

After this brief pause erection of the metalwork continued, and the critical operation of linking the four legs was successfully completed by March 1888.

In order to precisely align the legs so that the connecting girders could be put into place, a provision had been made to enable precise adjustments by placing hydraulic jacks in the footings for each of the girders making up the legs.