Re: what is the purpose of the bell shaped
I am just trying to think a bit more abstract here. Maybe the reason for making a bulge of some sort at the end of the pipe is to allow for upside down hanging? It also forces the smoke to be in contact with the water that much longer, but that length is negligible.
But I agree, it's probably mostly a visual thing. I mean if every single thing had a function and that's it, our hookahs would be 1 color, a single pipe running down with no chamber looking things, straight hose connector etc. I have a feeling they do it because is not that hard and it seems unbalanced to make an extremely ornate top part then leave the bottom as a straight pipe.