Hero of Alexandria

Water, when heated, is converted into air, and this air, by its expansive force, can produce motion.

The principle of the siphon is that water, when flowing from a higher to a lower level, will draw after it the water in the intermediate tube.

Nature abhors a vacuum.

The steam engine, or aeolipile, demonstrates how a rotary motion can be produced by the action of steam.

By means of a lever, a small force can overcome a great resistance.

The five simple machines are the lever, the wheel and axle, the pulley, the inclined plane, and the wedge.

The center of gravity is that point about which all parts of a body are equally balanced.

To construct a machine is to apply the principles of nature to the needs of man.

The screw is a continuous inclined plane wrapped around a cylinder.

Light travels in straight lines.

The angle of incidence is equal to the angle of reflection.

Mirrors can be used to create illusions and to magnify objects.

The path of light from a source to a mirror and then to an observer is the shortest possible path.

By combining mirrors, one can create a variety of optical effects.

The dioptra is an instrument for measuring angles and distances.

By using the dioptra, one can accurately determine the height of objects and the distances between them.

The principles of geometry are essential for accurate surveying.

To measure the depth of a well, one must use a plumb line and the principles of similar triangles.

The dioptra can be used for astronomical observations as well as terrestrial measurements.

The automaton is a machine that imitates the actions of living beings.