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Comment by nomel | Hacker News Reader

> Surface of revolution is okay

But surface, by definition, has no concept of thickness, right? Surely there's a better term?

> 'solid' would mean its interior is completely filled.

I think the easiest way to define a bell would be the difference of two solids of revolution (front surface, back surface). What do you call the difference of two solids of revolution?

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I meant it from a numerical analysis/differential geometry perspective (the reason I attached the reference). While not being strictly a surface, it is characterized by a mid-surface, and a thickness t. After having that information, for each point in the mid surface, a normal vector is drawn and scaled by a magnitude of t/2 in both directions of the normal, giving a thickness of t to the object that, I should have made it clearer, is not a surface but characterized by one.

I don't think that a bell is correctly modelled as a shell of variable thickness. The inner surface is smooth, and the outer surface has ridges. These ridges are apparently important to the timbre, thus it may be more appropriate to consider it as a solid volume of arbitrary shape. Of revolution, if you want to stay with a one-dimensional model.

Nah, the mouldings are entirely decorative. And bells are tuned by taking off material on a lathe at various positions on the inside of the bell.

https://funwithbells.com/nigel-taylor/

https://www.youtube.com/watch?v=JEJkMalMVv4

Wow, it's good to know, thanks for the clarification!

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