Thomas S. Crane

“ The friction of the jet must, therefore, tend to rotate a ball on an axis at right angles to the path of the jet, and, if this axis is not the shortest one passing through its centre of gravity, several oscillations, back and forth, must occur before the necessary adjustment is made. ”

“ Now blow through the quill Q steadily, and the ball B can be made to hang from or upon the under side of the jet J, being prevented by the string S from blowing away, and the atmospheric pressure A balancing the gravity G of the light ball. As the atmosphere presses nearly fifteen pounds upon a square inch, a ball one-quarter of a pound in weight would be balanced by the full pressure of the air upon a surface only 1/60 of an inch in area. It remains to notice the rapid revolutions of the ball and its uncertain axis of rotation when first suspended in the jet. ”

“ If a pin is stuck through the centre of the second card, into the opening of the quill, to keep it from sliding off, it will be found that no effort will blow the upper card from the first, as the current of air passing out between the cards destroys the atmospheric pressure between them, calling into play a force upon their outside surfaces that presses them tightly together. ”