We’re going to leave the lantern behind for a while and focus on the part of the library that holds it up: the upper dome. This section is somewhat plainer and more traditional, and provides a bridge between the baroque fussiness of the lantern with the Greek Revival façade below.
First we have a few details to attend to. The well-shaped floor of the lantern provides a drainage system for rain and snow, and support for the interior structures that, in turn, support the carillon bells. The 12 columns match the 12 interior columns of the lantern.
The transmission wires pass through an opening in this floor, connecting the bells to the keyboard below. More on this later.
To create the exterior lantern deck, we’ll cut down the lantern again to a single section, and bridge the space between the scrolls and extend it.
After the section is duplicated back out and the full lantern mesh is restored, we extrude the edge polygons vertically to create the railing base.
The railing consists of three rings connected by 120 upright posts, with every sixth post extended to provide support. So we’ll start with a 120-section polygonal ring.
All but one of the sections are deleted, and that one is duplicated twice, vertically. Two of the copies are connected with a short vertical post.
The sections are duplicated horizontally to make a six-section panel, and one vertical post is extended to connect all three rows.
The panel is now duplicated 19 times – for a total of 20 panels – and merged to build out the entire railing. The three horizontal railings are positioned vertically to move the railing into place.
The cladding for the dome consists of 70 copper sections. This is a simple shape and can be put in place quickly.
As for the dome wall, we’ll concern ourselves with only the top level – very little of this will appear in the final rendering. The dome has 14 sections instead of 12, resulting in a remarkable optical illusion that makes it appear to match the geometry of the lantern. Instead of a dodecagon, the dome is a tetradecagon. But when viewed from below it’s almost impossible to tell that the plans are different.
The flat tops of the columns will eventually support 14 carved owls. But we’ll leave those for later. It’s time to install the carillon bells.