This is a teaching aid to demonstrate the conversion of mechanical energy into heat; it consists of a small brass cylinder (diameter 1.2 cm, height 11 cm) which is mounted vertically on a wooden base (22 cm x 34 cm). The cylinder can be made to rotate by pulling alternatively the wooden handles on a string wound once around the cylinder; for a part of its height the cylinder is between two wooden shoes covered with felt; one of these is a part of the support and the other holds it more or less tightly by means of screws.
The apparatus is rather coarse and not pleasing to the eye, but it is quite effective as a teaching aid: if the cylinder full of water is made to rotate, the friction produced by the rubbing on the felt develops heat and the water is brought to the boiling point and the steam produced expels the cork stopper closing the cylinder.
The apparatus is a modified version of the one invented by John Tyndall (1820-1893) in which the cylinder is attached at the centre of a horizontal pulley which is made to rotate by means of a belt which in turn is made to rotate by a larger pulley that is rotated by hand.
The cylinder, full of water and closed with a cork stopper, rotates between the shoes of a wooden clamp covered with felt held tightly by hand.


Bibliografia:
Boutan - D'Almeida (1867); T. I, p. 315
Drion - Fernet (1883), p. 333
Frautschi - Olenick - Apostol - Goodstein (1988), p. 413
Segnini - Vergara Caffarelli (1990), p. 28


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