The claimed Voynich page

[asteckley]

Matching the height of the cover of the Voynich MS to 235 mm, I get that the text in the Voynich MS is roughly 9% larger.

That's awesome, thankyou! I got similar results. 

Depending on my exact lines, I got ~9.5% height difference, and ~7.5% width difference. The exact numbers depended on the exact rotation and choice of where to draw the boundaries. A stray word, longer space or including downwards tails/flourishes somewhere skews the numbers slightly. Using the top loops of the p and the top crossbar of the p makes a difference etc etc 

But the copy is always clearly smaller than the VMS.

I’ve been catching up on this interesting thread. I don’t have time to do a full analysis myslf right now, but I wanted to suggest something to both of you—eggyk and oshfdk—since your posts suggest you have the necessary technical skills.

So far, it seems you’ve been comparing the VMS folio and the copy by looking at selected heights and widths. If you’re willing to take it further, here’s an approach that might yield more insight:

• First, select several dozen anchor points from identical locations on both folios—the more points, the better. These should be clearly identifiable features that correspond between the two documents, such as specific points in the script or details in the plant drawings. Ideally, the points should be distributed across the entire page.
  
• Next, analyze the distances between pairs of these points, recording the corresponding measurements from each document. Instead of comparing just a few heights and widths, this gives you a large set of distances taken at different angles and from many locations across the page.
  
• From there, create a visual map showing the distortion vectors (both magnitude and direction) across the entire page.
  

The goal of this process would be to determine whether the distortion between the two documents forms a continuous pattern. And more specifically, a pattern that could suggest the use of an optical aid—perhaps one that was slightly tilted or periodically repositioned during the copying process.

Earlier in the thread, the possibility of a camera lucida was mentioned. But as we know, this device wasn’t invented—or at least wasn't patented—until the early 1800s, although that doesn’t necessarily rule out some inventive individual's use of one earlier. However, if the document is genuinely from an earlier period, a more plausible explanation might be the use of a concave mirror projection setup, as described by Hockney.

It was mentioned earlier in this thread that Hockney’s theory (i.e. the Hockney–Falco thesis) is not well respected. That’s not entirely accurate, or at least not particularly relevant here. While there is debate about his broader claims regarding the role of optical devices in the development of Western/Renaissance art, it is far less controversial that such optical tools did exist and that they were used during the Renaissance—centuries before the invention of the camera lucida.

A concave mirror projection system (or a camera lucida for that matter) could be indicated by a smoothly varying distortion across the page (or disjointed pattern of such distortions). It could also account for the combination of strong agreement in overall structure—such as in the drawing and general layout of the script—alongside the inaccuracies in finer details like individual glyphs or leaf edges. These projection systems do not produce perfectly sharp images. Even a skilled user might accurately capture the main elements of a page while struggling to resolve finer details clearly. So if they simply "did their best" and filled in glyphs and details that they couldn't make out clearly, it could easily result in the kind of mixed precision observed here.

(It could also explain the gross departure of the root system from the VMS original -- that lower section may have been entirely "off-screen". Or the person just got tired and decided to abandon the tedious equipment and free-hand his own root system.)