@robinhouston yes but I couldn't find it again last time I looked.

Anyway the letter was very polite and gave like eight reasons why the cans had the dimensions they actually did, rather than some theoretical local minimum.

For example

1. Cans move around the canning plant on tracks of a fixed width. To change can height is easy. To change can width requires rearranging the whole.plant.

2. Can lids are prefabicated and delivered to the plant in one of several standard sizes that matches the width of the cans which is dictated by the width of the rails etc.

3. Can thickness is not uniform. Can lids are thicker than can walls. So optimizing for weight and cost of materials—which they had done—produces a taller narrower can than the mathematician said.

Etc.