Francesco di Giorgio Martini's sketchbook

[DG97EEB]

I don't think it is plausible, no. I strongly suspect the earlier common source...

I agree. I think we should look into Vegetius, as his works were the main inspiration for Kyeser, Taccola and Martini.

His Re Militaris was very popular for many centuries before the VMS.

I think it would be worthwhile looking into Northern Italian and South German copies of Vegetius.

Here's a lovely early 15th century Upper Rhine manuscript 
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Edit: Btw, it's absolutely full of different barrels. They don't look Voynich like to me but maybe someone wants to take a look at that aspect as well

Edit: these were in fact likely drawn by Guilo Grassi in Lauber's workshop according to Rainer Lang