Aptom, high flyers of Princeton University, was assigned to work with Edison after graduation. He was very dissatisfied with Edison, who had no diploma but taught himself, and often showed a sarcastic expression. However, a little thing fundamentally changed his attitude towards Edison. Once, Edison asked Aptom to calculate the volume of pear-shaped glass bubbles. Aptom nodded and thought about such a simple thing for a while. I saw him bring pear-shaped glass bubbles. I measured it up and down several times with a ruler, then drew a sketch on the paper according to the style and listed a formula. After calculating, I still don't understand. In a row in dozens of formulas, or no results, Aptom was flushed, flustered. Edison waited for a long time in the laboratory, but he was surprised to find that there was no result. He went to Aptom's workshop and saw many formulas on a few pieces of white paper. He smiled and said, "It's a waste of time for you to calculate like this." . Edison brought some water, poured it into a glass bubble, handed it to Aptom and said, "Find another measuring cylinder, and you will know the answer." Aptom was inspired and eventually admired Edison, and eventually became a good assistant in Edison's career.