  In these notes we discuss some relations between complex analysis
(derivatives of Cauchy integrals) and curvatures of curves and surfaces. In
higher dimensions the Cauchy integrals are based on generalizations of complex
analysis using quarternions or Clifford algebras. These topics came up in
"Analysis of and on Uniformly Rectifiable Sets" (with Guy David, American
Mathematical Society, 1993), and here we describe some of the basic points
involved. A presentation based on this paper was made at the AMS Special
Session "Surface Geometry and Shape Perception" (Hoboken, 2001).
