The site is quite interesting as some of the same data is graphed or shown in a set of my father's International Correspondence School Textbooks For Mechanical Engineerig from 1924.
All the principles of elementary mechanics are presented and derived graphically. There is a chapter on Kinematics, forces being the cause of motion.
All the formulas/theorems/theory are presented and proven graphically using only algebra, trigonometry and geometry.
Some of the resolutions of problems of motion and forces in a steam engine are quite complex. I tried to do the graphical solutions on the computer and it presented a few problems. I can just imagine my father or anyone else with nothing more than a scale and compass working these problems out under an oil lamp.
