Cannons versus Pipes

[Mark Knowles]

The questions he did ask are much more relevant and remain unanswered.

I am not sure that they are more relevant. In both cases the questions relate to the absence of the drawing of certain specific details. I wouldn't view it as an objection to the "pipes" idea that there is no illustration of the water flowing into the pipes(certainly not from the central rosette), as with many illustrations these are not exact copies of reality, but generally simplified. I don't view what RobGea mentioned as problematic at all.