Folks,

The person who first drew a supply and demand diagram with P on the 
vertical axis was Karl Heinrich Rau, not "Johannes" Rau, as I mistakenly 
wrote earlier.  It was in the second edition of his Grundzatze der 
Volkwirthschastlehre, published in 1841 (first edition, 1826).

He was one of the German "proto-neoclassicals."  A good source on them 
is Erich W. Streissler, "Rau, Hermann and Roscher: contributions of 
German economics around the middle of the nineteenth century," European 
Journal of the History of Economic Thought, September 2001, vol. 8, 
issue 3, pp. 311-331.  

Sorry about the incorrect first name.

Barkley Rosser