At NIH my plan was to increase the quantity of small cells produced with the filtration technique, while minimizing perturbations, by employing a larger vessel capable of rapidly pushing liters of cells through a thick stack of filter papers. To accomplish this, a skilled machinist constructed a filter holder from a large stainless steel pipe, 12 cm in diameter and 40 cm long. A removable cap was clamped to the top and attached to a cylinder of compressed air to produce the pressure needed to push the culture through the filter stack. When it was completed, Don and I walked across campus to the machine shop to run the first test. After it was all set up and the top was clamped securely and attached to the air cylinder, we all stood as far back as we could and one of us, the machinist I believe, turned the valve on the cylinder. There was an immediate sound of a canon having been fired in this cavernous, high-ceilinged room. At the time I thought the entire apparatus had been blown into the air with a thunderous roar. We all dove for cover. It turned out to be just the cap. The only subsequent sound was my voice saying “has it come down yet?” a comment Don joked about for many years thereafter with anyone willing to listen to this story about our underestimation of the importance of pressure regulation. The device was eventually properly strengthened and regulated, and I began running tests with it