The sundial is no doubt the oldest known device used to measure time and by extension, it is therefore the most ancient scientific instrument. It operates by casting a shadow of an object that moves from one side to the other as the sun travels (relatively speaking, of course) from east to west throughout the course of the day.
To accomplish this, all the ancients needed was a vertical stick or pillar or a tree, heck anything that stuck out of the ground. If the ancients could command someone to stand still for the duration of the day, then they have the essentials of a sundial. The length of the shadow that is cast will tell them the time.
The Babylonians and the Egyptians built obelisks, those tall pointed needles that shot straight up into the sky, and the moving shadows that it cast allowed them to have a kind of sundial. This enabled the observers, in this case, their population, to divide the day at the very least into two parts, deliniated by noon time when the shadow disappeared. They could have instituted markings around the base of the monument as an improvement, because it would show additional time divisions, which of course increases their time telling accuracy: they would have gone from, hey, it’s morning/afternoon, to hey, it’s three divisions in the afternoon. Or, don’t wake me up, it’s only one division in the morning.
The earliest known sundial that exists today is an Egyptian shadow clock. It has a straight base with a raised needle at one end. The base is inscribed with six time divisions, and is oriented east-west with the needle shadow located at the east end in the morning, and by the afternoon, it would be located on the west end.
The earliest recorded description of a sundial is noted by a Babylonian priest and author. His description of a sundial is a cubical block into which a half-sphere is carved. In lieu of a needle, a small bead is employed at the center. Throughout the day the shadow of the bead travels in a circular arc. The arc is divided into twelve equal parts. Given that the length of the day varies with the season, the hours likely varied in length from one season to another. Not until the advent of the mechanical clock would we have the ability to tell time in equal divisions, not subject to the changing shadow that accompanied the changing seasons.
Of course, no discussion about the history of anything is complete without looking at the Romans and what they have done. The Romans are master assimilators (resistance is futile) and they assimilated their sundial technology from the Samnites. They of course improved upon their captured technology (unlike those guys in the cubes) and the first sundial constructed for the city of Rome was designed by famed architect Marcus Vitruvius Pollio (yes, a long and masterful sounding name — oh, so Roman). Read about his exploits in his masterpiece “De Architectura.”
And what would be a discussion involving obvious geometric patterns without inclusion of the Greeks? These guys developed and constructed complex sundials using their knowledge of geometry: Apollonius developed the hemicyclium by using a surface of conic section, thereby increasing accuracy and Ptolemy (whose lineage would produce the sexy Cleopatra, but anyway I digress) used the analemma, an invention that enabled shadows to be projected onto flat surfaces that were inclined at various angles relative to the horizontal. One of the many notable time-telling pieces attributed to the Greek is the Tower of the Winds in Athens, which is an octagonal structure containing eight sundials.
At some point after the Greeks and the Romans, it was discovered that the shadow cast by a slanted object is more accurate than that cast by a vertical object. Parallel to the earth’s axis is ideal for accuracy, but rather impractical for casting shadows, but hey, they tried.
The Greeks would later introduce trigonometry into mathematics, thus providing the means for plotting hour lines with simple mathematic calculations in lieu of unwieldy geometric constructions. Thank you Greeks, said the Arabs and later the European sundial makers.
The sundial is no doubt the oldest known device used to measure time and by extension, it is therefore the most ancient scientific instrument. It operates by casting a shadow of an object that moves from one side to the other as the sun travels (relatively speaking, of course) from east to west throughout the course of the day.
To accomplish this, all the ancients needed was a vertical stick or pillar or a tree, heck anything that stuck out of the ground. If the ancients could command someone to stand still for the duration of the day, then they have the essentials of a sundial. The length of the shadow that is cast will tell them the time.
The Babylonians and the Egyptians built obelisks, those tall pointed needles that shot straight up into the sky, and the moving shadows that it cast allowed them to have a kind of sundial. This enabled the observers, in this case, their population, to divide the day at the very least into two parts, deliniated by noon time when the shadow disappeared. They could have instituted markings around the base of the monument as an improvement, because it would show additional time divisions, which of course increases their time telling accuracy: they would have gone from, hey, it’s morning/afternoon, to hey, it’s three divisions in the afternoon. Or, don’t wake me up, it’s only one division in the morning.
The earliest known sundial that exists today is an Egyptian shadow clock. It has a straight base with a raised needle at one end. The base is inscribed with six time divisions, and is oriented east-west with the needle shadow located at the east end in the morning, and by the afternoon, it would be located on the west end.
The earliest recorded description of a sundial is noted by a Babylonian priest and author. His description of a sundial is a cubical block into which a half-sphere is carved. In lieu of a needle, a small bead is employed at the center. Throughout the day the shadow of the bead travels in a circular arc. The arc is divided into twelve equal parts. Given that the length of the day varies with the season, the hours likely varied in length from one season to another. Not until the advent of the mechanical clock would we have the ability to tell time in equal divisions, not subject to the changing shadow that accompanied the changing seasons.
Of course, no discussion about the history of anything is complete without looking at the Romans and what they have done. The Romans are master assimilators (resistance is futile) and they assimilated their sundial technology from the Samnites. They of course improved upon their captured technology (unlike those guys in the cubes) and the first sundial constructed for the city of Rome was designed by famed architect Marcus Vitruvius Pollio (yes, a long and masterful sounding name — oh, so Roman). Read about his exploits in his masterpiece “De Architectura.”
And what would be a discussion involving obvious geometric patterns without inclusion of the Greeks? These guys developed and constructed complex sundials using their knowledge of geometry: Apollonius developed the hemicyclium by using a surface of conic section, thereby increasing accuracy and Ptolemy (whose lineage would produce the sexy Cleopatra, but anyway I digress) used the analemma, an invention that enabled shadows to be projected onto flat surfaces that were inclined at various angles relative to the horizontal. One of the many notable time-telling pieces attributed to the Greek is the Tower of the Winds in Athens, which is an octagonal structure containing eight sundials.
At some point after the Greeks and the Romans, it was discovered that the shadow cast by a slanted object is more accurate than that cast by a vertical object. Parallel to the earth’s axis is ideal for accuracy, but rather impractical for casting shadows, but hey, they tried.
The Greeks would later introduce trigonometry into mathematics, thus providing the means for plotting hour lines with simple mathematic calculations in lieu of unwieldy geometric constructions. Thank you Greeks, said the Arabs and later the European sundial makers.
Post Published: 27 September 2009
Author: Sun Staff
Found in section:
Sundial
