When a machine was perfected, giving an unusually long spark, he always liked to take me over at night to the shop to see it perform. I well remember the last time,—at Wei Hsien. At one end of the shop was the windmill. Here he stopped to show me a way of equalizing the stroke of the windmill pump piston, by hanging on an old kettle of scrap iron. Then he took me into an inner room, where on one end of a long table stood the newly finished machine,—a beauty, no mistake. Having forgotten some necessary key, he took the lantern and went to get it, leaving me in the dark. I noticed sounds, the dripping of water in the well; but what was the ticking I heard? On the return of the lantern I saw the cause,—a number of clock dials all hung on the wall, and all to be run by one clock by means of electricity. These were for the college recitation rooms when they should be finished. Then Calvin made the new machine do its work. Adjusting carefully the mechanism, and then measuring the spark, he exclaimed with boyish glee, “There, isn’t that a beauty!” Dr. W. A. P. Martin, of Peking, related in the “Chinese Recorder” of December, 1908, this incident as to Dr. Mateer: “It was once my privilege to spend part of a vacation in his hospitable home at Tengchow. I found him at work constructing scientific apparatus with his own hands and wrestling with a mathematical problem which he had met in an American magazine. When I solved the problem, he evinced a lively satisfaction, as if it were the one thing required to cement our friendship.” The problem was to find the diameter of an auger, which, passing through the center of a sphere, will bore away just one half of its bulk. It is easy to see that to a man of that sort his work and the scientific and practical problems constantly arising in connection with the making of apparatus and the adjustment of machinery must have been in themselves a rich source of pleasure, though he never allowed himself to be so fascinated by his shop as to break in on what he conceived to be his higher work. Speaking of his last years, Ada says: “He would go out wearied with the baffling search for a way of expressing clearly in Chinese a thought none too clear in the original Greek, his forehead grooved with the harrows of thought. He would come back from the shop an hour later, with well-begrimed hands, a new spot on his long Chinese gown, a fresher pink in his cheeks, a brighter sparkle in his eyes, and his lips parted with a smile. Then, having washed, he would immediately set himself again to the work of revision.”