A gyroscope is not an ordinary top. It is like a heavy fly wheel, revolving on an axis; and if it is spun, the speed of the revolutions maintains the axis in the perpendicular. A huge gyroscope is used to steady the channel steamers, which would otherwise stagger and reel. A gyroscope has just been adopted to the monorail cars, and so long as the gyroscope gyrates the monorail car cannot stagger or reel. If a proper gyroscope was placed on the end of a knitting needle and gyrated at full speed, that knitting needle could be stood on end and it would not fall over. Therefore, if a gyroscope was placed in the top of a top hat, and the top hat firmly fastened to the head of a man, and the gyroscope set going, that man would remain perpendicular in spite of anything. He could not stagger. He could not reel. He could walk a line as straight as a crack. When I had completed this gyro-hat I showed it to my wife, and briefly explained what it was and what I meant to do with it. The small but wonderfully powerful motor and the gyroscope itself were all concealed inside the hat, and I explained to my wife that Walsingham Gribbs need but fasten the hat firmly on his head and he would never stagger again. At first my wife seemed doubtful, but as I went on she became enthusiastic. The only thing she disliked was the method of fastening the hat to the head, for, as it was quite necessary that the hat be very firmly fixed to the head, I had sewed ear tabs to the hat, and these I tied firmly under my chin. My wife said she feared it would require some time to persuade the public to take to silk hats with ear tabs, and that the sight of a man in a silk hat with ear tabs would be a sign that he was a staggerer. She wanted another method of holding the hat on the head. “Vacuum suction,” I said, for I am quick to catch an idea. A man has to be, in the hat business. “But,” I added, “where would you get the vacuum? A man cannot be expected to carry a can of vacuum, or whatever he would need to carry vacuum in, around with him; especially the kind of man that would need the gyro-hat.” [Illustration: “‘MY DEAR,’ SAID MY WIFE, ‘I HAVE IT. LET THE HAT MAKE ITS OWN VACUUM.’”] “My dear,” said my wife, after a minute of thought, during which we both studied the gyro-hat, “I have it! Let the hat make its own vacuum. If the hat is lined with air-tight aluminum, and has a rubber sweat band, and an expulsion valve, the gyroscope motor could pump the air out itself. It could create its own vacuum.” “Of course it could!” I exclaimed. “I could rig it up so that putting the hat on the head would start the gyroscope, and the gyroscope would pump a vacuum. All any staggerer would need to do would be to put on his hat, and the hat would do the rest. It would stay on his head and it would keep him evenly on his keel.” (Of course I would not use a nautical term like “keel” in my hat shop, but at home I allow myself some liberties of that sort.)