A Bridge Pretty Darn Far

CARL LONG taught a course on structures which I took in the seventies. Part of the course dealt with the design of trusses, in this case specifically to support a bridge. Our class of about ten had studied designs for a week or so with Long gently bringing us through the time-consuming and arduous math to determine the deflection of the truss under load and the stresses in each member. We used calculators and laboriously worked through each calculation.

One day in class Long asked if we were ready to be examined on the truss designs. We nodded affirmatively and he drew a complex truss on the board, complete with loads and dimensions, freehand. We began work on the analysis while Long spent a minute examining his drawing. He suddenly stopped us, walked up to the board, and changed several values of loads and lengths. "Try it now," he said. "I changed it so your answers will all come out as whole numbers."

Here he had completed all the calculations in his headcalculations that took us a half hour to do on the calculators and then recalculated the elements so that the answer would come out in whole numbers.

Simply amazing.