Pre-dating Heron's writings, a device called an aeolipile was described in the 1st century BC by Vitruvius in his treatise De architectura; however, it is unclear if it is the same device or a predecessor, as he does not mention rotating parts.

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The protocols and practices of dating, and the terms used to describe it, vary considerably from country to country and over time.

While the term has several meanings, the most frequent usage refers to two people exploring whether they are romantically or sexually compatible by participating in dates with the other.

Opposite to the extremity G place a pivot, L M, resting on the lid C D; and let the ball contain two bent pipes, communicating with it at the opposite extremities of a diameter, and bent in opposite directions, the bends being at right angles and across the lines F G, L M.

As the cauldron gets hot it will be found that the steam, entering the ball through E F G, passes out through the bent tubes towards the lid, and causes the ball to revolve, as in the case of the dancing figures.

When the vessel is pressurized with steam, steam is expelled through the nozzles, which generates thrust due to the rocket principle as a consequence of the 2nd and 3rd of Newton's laws of motion.

When the nozzles, pointing in different directions, produce forces along different lines of action perpendicular to the axis of the bearings, the thrusts combine to result in a rotational moment (mechanical couple), or torque, causing the vessel to spin about its axis.

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Dating as an institution is a relatively recent phenomenon which has mainly emerged in the last few centuries.

From the standpoint of anthropology and sociology, dating is linked with other institutions such as marriage and the family which have also been changing rapidly and which have been subject to many forces, including advances in technology and medicine.

This can be seen in the illustration of a classroom model to the right.