The "spokes" on the rosettes folio

[-JKP-]

There are several spoke-like patterns on the rosettes folio.

They could be domes, tents, water wheels (like a mill wheel), fountain cisterns, or any number of things.

A couple of them remind me of mill wheels, like this early medieval drawing (note the way the pipe and the water are drawn):



Wikipedia



British Library, The Lutrell Psalter


There are also water-lifting wheels for wells and for irrigation (also to move water out of mining sites).

For comparison to the western drawing, here is a Persian wheel:





Here's a further idea for the spoke wheels... some kind of crank mechanism... there were many different kinds of wheel-cranks in the Middle Ages and some were quite large (note that there are Ghibelline merlons):

[ReneZ]

I wonder if these last two illustrations are from a copy of Valturius: "De Re Militari"

[Wladimir D]

Ha ha. Sumptuously. This mechanism is a prototype escalator. The lifting platform is divided into 4 parts and turns into steps. With blue arrows I showed the axis of rotation. The load is placed on the top of the platform, and the horizontal position of this part of the platform (so that the load does not slip) is regulated through the blocks. Horizontal movement is carried out using a gear wheel.
   

[-JKP-]

Here's another example of spoke patterns, from the Chateau d'Angers. I don't know how far back this tradition goes, but it is not the most common kind of garden pattern:



Image courtesy of Ab2804, Wikipedia

There's also one with a spiral, which reminds of me of the circular drawings in the cosmology section.