When the numbers matter... It still amazes me how my grandfather could deduct the speed of a car by the skidmarks, rebuilding accidents in his head just by looking at the data. Probably not completely foolproof but still amazing physics and mathematics. I did save some of the sketches he made, some sort of technical drawings. If the bid on this one is high enough I'll mint those as a bonus. Chalk was used to visualize the trajectory of the vehicles involved. In these photographs it often creates a focus point where otherwise there would be none. Sometimes the chalk almost seems burnt into the image. Pure white in sharp contrast to the brutality of a car crash.