Palatino 766 pipes, pools, cliffs, streams... (by Taccola)

[Bernd]

Good find in sphaera mundi! I am quite certain Taccola didn't invent this Sun-shape.

It would be helpful to look into the primary sources. I have this article:
Shelby, Lon (1975). "Mariano Taccola and His Books on Engines and Machines". Technology and Culture. 16 (3): 466–475. doi:10.2307/3103042. JSTOR 3103042.

The genesis of De ingeneis covered a thirty-year period. Around 1419 Taccola began making technical drawings and notations which he called capitula and which eventually went into the composition of book 1 of De ingeneis. During the 1420s he added book 2, and by 1433 he had completed books 3 and 4. Books 1 and 2 got separated from books 3 and 4, and the latter apparently got out of Taccola's possession, for they remained in the form in which he originally composed them. On the other hand, he continued to work over books 1 and 2 by adding-in and around the original drawings-hundreds of notes and other drawings which Prager and Scaglia designate as the "Sketches." He also made notes and drawings on folios that were added to the original manuscript of books 1 and 2; these folios the editors have designated as the "Separate Fascicule" and the "Sequel." They tentatively date the "Sketches" to the period 1433-38; the "Sequel" to 1438-49, and the "Separate Fascicule" to the period just before 1449. It was in that latter year that Taccola completed his other treatise, De machinis, which restated in ten books many of the devices developed in the long and complex genesis of its predecessor, De ingeneis.

BNCF, Palatino 766 consists of De ingeneis 3+4, which according to Shelby were not in Taccola's possession soon after he completed them. So who had it then and how did it get into the possession of BNCF?

If we assume that BNCF, Palatino 766 was a direct inspiration for the VM, I think this hypothesis, if true, has fundamentally different implications than the other putative sources proposed so far. For they all existed in a number of widely known and circulated copies at the time the VM was created. This is not the case for Taccola's De ingeneis 3+4. No known copies exist in contrast to Taccola's other works. Furthermore, the first facsimiles were only published in the 1970s. The whole thing is quite bizarre, there still seems very little academic work done about Taccola. Furthermore, I'd like to point out that prior to the 70s it would have been considerably hard for a potential modern forger to get a look at this manuscript. The only way would have been direct access to the original at BNCF.