Nicola Giocoli poses an excellent question. For some perverse reason these
triangles of excess burden are now known as Harberger triangles, although
they surely antedate him.

I doubt if Joan Robinson is guilty: she was too smart and public-minded not
to recognize that they serve to trivialize excess burden by generalizing
from partial to general equilibrium.

I look forward to someone answering Nicola's question better than I can.

Mason Gaffney