After a long stalemate, the sundial gradually moved. -A?vagho?a Xi Zhong "The Legend of Zhongshan Wolf"

(2) A device that uses the shadow cast by the sun to measure time. Also known as "solar gauge", it is an ancient time measuring instrument in China that used the sun shadow to measure time. It usually consists of a copper pointer and a stone disk. The pointer made of copper is called "Gong Pin", which passes through the center of the disk vertically and acts as a neutral rod in the standard watch. Therefore, Gong Pin is also called "table", and the disk made of stone is called "Gong Mian". On the stone platform, the stone platform is high in the south and low in the north, making Gong Mian parallel to the equatorial plane of the sky. In this way, 12 large squares are carved on the front and back sides of the brick surface, and each large square represents two hours. When the sun shines on the sundial, the shadow of the sundial needle will be cast on the surface of the sundial, and the sun will move from east to west, and the shadow cast by the sundial needle on the surface will slowly move from west to east. Therefore, the moving shadow of the coffin needle seems to be the pointer of modern clocks and watches, and the coffin surface is the surface of clocks and watches to show the time.

From the vernal equinox to the autumnal equinox, the sun always runs on the north side of the celestial equator, so the shadow of the ray needle is cast above the ray plane; From the autumnal equinox to the vernal equinox, the sun runs on the south side of the celestial equator, so the shadow of the needle is cast below the surface of vernal equinox. Therefore, when observing the sundial, we must first understand the projection position of the sundial needle in two different periods.

The earliest sundial in the world was born in the kingdom of Babylon 6000 years ago. The earliest documentary record in China is the short shadow level, namely the horizon sundial, which was invented by Yuan Chong in the 14th year of Emperor Yangdi's reign in 574 AD. The clear record of the equatorial sundial was first seen in the shadow picture described in Volume 2 of Zeng Minxing's "Lonely Wake Magazine" in the Southern Song Dynasty.

The equatorial sundial usually consists of a copper pointer and a stone disk. The copper pointer is called "gong needle", which passes through the center of the disc vertically. The gong needle is also called "watch". The stone plate is called the "gong face" and placed on the stone platform, with the south high and the north low, so that the gong face is parallel to the equatorial plane, and the upper end of the gong needle just points to the north celestial pole, and the lower end is just right. 12 cubes are carved on both sides of the brick surface, and each cube represents two hours. When the sun shines on the sundial, the shadow of the sundial needle will be cast on the surface of the sundial, and the sun will move from east to west, and the shadow cast by the sundial needle on the surface will slowly move from west to east. Therefore, the moving shadow of the coffin needle seems to be the pointer of modern clocks and watches, and the coffin surface is the surface of clocks and watches to show the time.

This method of timing by sunlight projection is an important invention of human beings in the field of astronomical timing. This invention has been used by human beings for thousands of years. But the sundial has a fatal weakness, that is, it can't be used in rainy days and at night. It was not until 1270 that early mechanical clocks appeared in Italy and Germany, while China got two foreign clocks in 160 1. Therefore, it is still a modern thing to completely abandon the sundial and get to know Guang Chen by looking at the clock.

The production of sundial should not only point to the correct installation of the hour hand, but also point to the depiction of the time line. The timeline description of various sundials is related to the geographical position of sundials and the height of the hour hand. Suppose the geographical latitude is φ, the height of the hour hand is h, and the difference between the time to be marked and noon is t; The angle between the time axis and the hour hand is a, and the distance is d, then the calculation formula of each sundial is as follows:

(1) horizontal sundial: TAN(A)=TAN(T)*SIN(φ)

(2) Equatorial sundial: bisecting the disk, which is equivalent to 15 degrees per hour, and the noon line is vertically downward.

(3) polar coordinates: D=H*TAN( 15*T)

(4) Southward vertical sundial: TAN(A)=TAN(T)*COS(φ)

(5) East or west vertical type: D=H*TAN((6-T)* 15)

(6) Horizontal and vertical formula: tan (a) = sin (o) * tan (r+15 * t)

Refers to the angle between the hour hand and the vertical line of the wall, TAN(W)=SIN(θ)*COT(φ)

Refers to the angle sin (o) between the height of the hour hand and the wall surface = cos (θ) * cos (φ).

Refers to the time line difference between the hour hand and the noon line COT(R)=COT(θ)*SIN(φ)

The included angle between 6 o'clock and 12 time line COT(S) =SIN(θ)*TAN(φ).

θ: the oblique angle of the sundial wall.

(7) Projection sundial: D= SIN(T* 15), V= sin(φ)*COT(φ).

The ratio of major axis to minor axis of ellipse: sin(φ)

The position of the vertical pole (where people stand): Z=TAN(del)*COS(φ)

Del: the declination of the sun, and v: the value of the time point in the short axis direction.

D: The sundial, also called "sundial", is an ancient time-measuring instrument in China. It usually consists of a copper pointer and a stone disk. The pointer made of copper is called "Gong Pin", which passes through the center of the disk vertically and acts as a neutral rod in the standard watch. Therefore, Gong Pin is also called "table", and the disk made of stone is called "Gong Mian". On the stone platform, the stone platform is high in the south and low in the north, making Gong Mian parallel to the equatorial plane of the sky. In this way, 12 large squares are carved on the front and back sides of the brick surface, and each large square represents two hours. When the sun shines on the sundial, the shadow of the sundial needle will be cast on the surface of the sundial, and the sun will move from east to west, and the shadow cast by the sundial needle on the surface will slowly move from west to east. Therefore, the moving shadow of the coffin needle seems to be the pointer of modern clocks and watches, and the coffin surface is the surface of clocks and watches to show the time.

From the vernal equinox to the autumnal equinox, the sun always runs on the north side of the celestial equator, so the shadow of the ray needle is cast above the ray plane; From the autumnal equinox to the vernal equinox, the sun runs on the south side of the celestial equator, so the shadow of the needle is cast below the surface of vernal equinox. Therefore, when observing the sundial, we must first understand the projection position of the sundial needle in two different periods. China ancient time measuring instrument. It consists of a grating needle and a grating disk. The grating needle is perpendicular to the disk surface, and the time can be measured by the direction of the sun shadow on the disk surface. Due to the different directions of the disks, sundials can be divided into horizontal sundials, equatorial sundials, vertical sundials and inclined sundials. The early history of sundials is still unclear. The earliest reliable record is the short shadow level invented by Yuan Chong in the 14th year of Sui Kai (594) mentioned in Tian Wenzhi. The clear record of the equatorial sundial was first seen in the shadow picture described in Volume II of Zeng Minxing's "Lonely Wake Magazine" in the Southern Song Dynasty, but the dial was made of wood. Later, it was changed to stone grate plate and metal grate needle. The Forbidden City in Beijing and other places have preserved the stone equatorial sundial made in Qing Dynasty. The surface of the equatorial sundial is parallel to the equatorial plane, and its pointer points to the north and south poles. After a long stalemate, the sundial gradually moved. -A?vagho?a Xi Zhong "The Legend of Zhongshan Wolf"

(2) sundial: a device that uses the shadow cast by the sun to determine the time. Also known as "solar gauge", it is an ancient time measuring instrument in China that used the sun shadow to measure time. It usually consists of a copper pointer and a stone disk. The pointer made of copper is called "Gong Pin", which passes through the center of the disk vertically and acts as a neutral rod in the standard watch. Therefore, Gong Pin is also called "table", and the disk made of stone is called "Gong Mian". On the stone platform, the stone platform is high in the south and low in the north, making Gong Mian parallel to the equatorial plane of the sky. In this way, 12 large squares are carved on the front and back sides of the brick surface, and each large square represents two hours. When the sun shines on the sundial, the shadow of the sundial needle will be cast on the surface of the sundial, and the sun will move from east to west, and the shadow cast by the sundial needle on the surface will slowly move from west to east. Therefore, the moving shadow of the coffin needle seems to be the pointer of modern clocks and watches, and the coffin surface is the surface of clocks and watches to show the time.

From the vernal equinox to the autumnal equinox, the sun always runs on the north side of the celestial equator, so the shadow of the ray needle is cast above the ray plane; From the autumnal equinox to the vernal equinox, the sun runs on the south side of the celestial equator, so the shadow of the needle is cast below the surface of vernal equinox. Therefore, when observing the sundial, we must first understand the projection position of the sundial needle in two different periods.

A sundial, also known as a sundial, is a timer used by ancient people to set time by the shadow of the sun. There are many kinds of sundials, which can be divided into horizontal, equatorial, meridian and unitary according to their different positions, and their functions are also different.

The earliest sundial in the world was born in the kingdom of Babylon 6000 years ago. The earliest documentary record in China is the short shadow level, namely the horizon sundial, which was invented by Yuan Chong in the 14th year of Emperor Yangdi's reign in 574 AD. The clear record of the equatorial sundial was first seen in the shadow picture described in Volume 2 of Zeng Minxing's "Lonely Wake Magazine" in the Southern Song Dynasty.

The equatorial sundial usually consists of a copper pointer and a stone disk. The copper pointer is called "gong needle", which passes through the center of the disc vertically. The gong needle is also called "watch". The stone plate is called the "gong face" and placed on the stone platform, with the south high and the north low, so that the gong face is parallel to the equatorial plane, and the upper end of the gong needle just points to the north celestial pole, and the lower end is just right. 12 cubes are carved on both sides of the brick surface, and each cube represents two hours. When the sun shines on the sundial, the shadow of the sundial needle will be cast on the surface of the sundial, and the sun will move from east to west, and the shadow cast by the sundial needle on the surface will slowly move from west to east. Therefore, the moving shadow of the coffin needle seems to be the pointer of modern clocks and watches, and the coffin surface is the surface of clocks and watches to show the time.

This method of timing by sunlight projection is an important invention of human beings in the field of astronomical timing. This invention has been used by human beings for thousands of years. But the sundial has a fatal weakness, that is, it can't be used in rainy days and at night. It was not until 1270 that early mechanical clocks appeared in Italy and Germany, while China got two foreign clocks in 160 1. Therefore, it is still a modern thing to completely abandon the sundial and get to know Guang Chen by looking at the clock.