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J. Perelman
"Entertaining physics". Book 1.
Chapter 6. Thermal phenomena


Ancient Greek mechanical engineer Heron of Alexandria, the inventor of the fountain that bears his name, has left us a description of two ingenious ways in which the Egyptian priests deceive the people, instilling in him a belief in miracles.

Figure 1 you see a hollow metal altar, and beneath it hidden in a dungeon mechanism driving the doors of the temple. The altar stood outside it.

Fig. 1. The unmasking of the “miracle” of the Egyptian priests: the doors of the temple opened by the action of a sacrificial fire.

When there is a fire, the air inside the altar the heat stronger pressure on the water in the vessel, hidden under the floor; from the vessel, the water is pushed out of the tube and poured into the bucket, which, falling, actuates the mechanism that spins the door (Fig. 2).

Fig. 2. Diagram of the device of the doors of the temple, which are open when on the altar of the blazing fire (cf. Fig. 1).

The amazed spectators, unaware of hidden under the floor installation, see the “miracle”: once on the altar will burn the fire, the doors of the temple, “give heed to the prayers of the priest”, dissolve like themselves...

Another imaginary miracle, arranged by the priests depicted in Fig. 3. When on the altar will burn the flame, the air expands and displays the oil from the bottom of the tank into the tube, hidden inside the figures of the priests, and then the oil miraculously itself pouring into the fire... But it was worth the priest, the head of this altar, quietly remove the cap from the vessel - and the outpouring of oil was stopped (because the excess air can freely go through the hole); to this trick priests resorted to when the offering was praying too poorly.

Fig. 3. Another imaginary ancient miracle: the oil itself is pouring into the sacrificial fire.

Entertaining physics J. Perelman


System Orphus


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