In Fleeming Jenkin's PAPERS: LITERARY, SCIENTIFIC, &c, his article on "The  
Graphic Representation of the Laws of Supply and Demand, and Their  
Application To Labour", originally published in RECESS STUDIES in 1870, he  
illustrates the demand and supply curves in diagrams that use the horizontal  
axis for shillings and the vertical axis for quantities of quarters of wheat  
in figures 1-9.  In the other four figures, prices continue to appear on the  
abscissae, with quantities on the ordinates.  
  
In his "On the Principles Which Regulate the Incidence of Taxes", from the  
Proceedings of the Royal Society of Edinburgh, Session 1871-2, he continues  
to use the same convention for prices and quantities in all five figures.  
  
Samuel Bostaph