The gap left by attacking Chapter 5 before Chapter 4 has now been filled in. I think it should now read continuously from the start to the end of Chapter 5 (so far). Some loose ends to be tidied up, though.
Chapter 4 is on hold because of a need to get Chapter 5 drafted. That chapter now has a lot of content, mainly about plucked-string instruments but a bit about the vibration behaviour of violin bodies as well.
A complete draft of Chapter 3, on tuned percussion instruments, is now in place
A first complete draft of Chapter 2 has now been added, and Chapter 3 is beginning to take shape.
First effort to get something launched. Good so far…