Problem Geometry

How, exactly, do you connect the top of a wood-framed spire?

There are eight diagonal timbers – defining the corners of the octagonal spire – converging at the same location where you have to attach a central mast to carry the spire-top cross. The short answer is that you can’t do it all there, at the apex, you have to spread the connections out a bit to get room. The eight main ribs are attached to one another a few feet down from the apex – in the photo, in the area where the copper sheathing was not removed – where there’s room to install blocking and bolts between the ribs. Technically, the very tops of the ribs are cantilevered up from those connections.
The base of the mast is bolted to a built-up wood box, which extends down between the main ribs to the same connections that fasten the ribs. Note that the black is the original tar waterproofing.

After some repairs, the new waterproofing is installed:

Then the copper sleeve at the base of the mast/top of the spire is put back:

Then a big copper ball as ornament:

And once completed:

As a bonus, some nice views of the Bronx in the background. My thanks to Ellen for the pictures.

My general theory – that the people who designed and built these buildings were incredibly clever to accomplish so much with so few tools compared to what we have today – holds true again.