> What is the history of the trick to find the indefinite inteegral of the > secant function? Who first used it, and when?
For the history of the integral of the secant function, see e.g.
The Story of Mercator's Map.: A Chapter in the History of Mathematics H. S. Carslaw The Mathematical Gazette, Vol. 12, No. 168 (Jan., 1924) <http://www.jstor.org/stable/3603395>
An Application of Geography to Mathematics: History of the Integral of the Secant V. Frederick Rickey and Philip M. Tuchinsky Mathematics Magazine, Vol. 53, No. 3 (May, 1980), pp. 162-166 <http://www.jstor.org/stable/2690106> -- Robert Israel israel@math.MyUniversitysInitials.ca Department of Mathematics http://www.math.ubc.ca/~israel University of British Columbia Vancouver, BC, Canada