NavList:

Frank,

   Thank you for providing this paper. It contains the following paragraph that speaks to my earlier comment to Stan

"Wright also offered an interesting physical model. Consider a cylinder tangent to the earth’s equator and imagine the earth to “swal {swell] like a bladder.” Then identify points on the earth with points on the cylinder they come in contact with. Finally unroll the cylinder; it will be a Mercator map. This model has often been misinterpreted as a cylindrical projection (where a light source at the earth’s center projects the unswollen sphere onto its tangent cylinder), but this is not conformal."

For this physical model to work I think you'd have to add the requirement that once a point on the surface of the bladder touches the inside of the cylinder it sticks and can move no more.

It may be that Bowditch's statement that "The Mercator projection is not perspective, and its parallels can be derived mathematically as well as projected geometrically. " is an example of the misinterpretation of the model "as a cylindrical projection (where a light source at the earth’s center projects the unswollen sphere onto its tangent cylinder)" and not an referring to the graphical construction as I suggested previously,

Regards,

Robin Stuart