How did the ancients use the light and shadow of the sun to keep time?

The ancients used instant tools such as sundials and watches to keep time.

Sundial: The first floor is almost copied.

The ancients used the sun to keep time through sundials.

Sundial, in its original meaning, refers to the shadow of the sun. The modern "sundial" refers to a kind of timekeeping instrument that used the shadow of the sun to measure the time in ancient times, also known as the "daily rule". The principle is to use the direction of the sun's projection to determine and divide the time, which usually consists of a dial hand (watch) and a dial (a dial base).

The method of using sundials to keep time is a major invention in the field of astronomical timekeeping, which has been used by mankind for thousands of years.

How sundials work:

Over the course of the day, the shadows cast by objects illuminated by the sun are constantly changing:

The first is that the length of the shadow is changing. The shadow is longest in the morning, and as time goes on, the shadow becomes shorter, and after noon it becomes longer again;

The second is that the direction of the shadow is changing. North of the Tropic of Cancer, the morning shadow is in the west, the noon shadow is in the north, and the evening shadow is in the east. In principle, it is possible to time according to the length or direction of the shadow, but it is more convenient to time according to the direction of the shadow.

Therefore, it is usually timed in the direction of the shadow. Over time, the shadow on the sundial slowly moves from west to east. The shadow of the moving dial hand resembles the hands of a modern clock, and the dial face is the surface of the clock, which shows the time.

In the morning, the shadow is cast near the hour at the western end of the plate; When the Sun reaches its highest position due south (Upper Midheaven), the shadow of the needle is located due north (lower), indicating the time of noon in the local area. In the afternoon, the sun moves westward, and the shadow of the sun slants eastward, pointing to the hours of Wei, Shen, and You.

The Chinese invented the "sundial" for timekeeping, which is the most accurate "astronomical clock".

In ancient times, people used sundials, watches, and water clocks to keep time.

The shadow of an object under the sun changes in five stages of a day, and the ancients used the projection of the sun to divide the time

You can look up the sundial, which is the instrument used by the ancients to keep time with the sun.

Salt drying is probably the earliest technology used by the ancients to use solar energy.

In ancient times, solar energy was used to make fire, as well as ice lenses and fire beads. According to the 2nd century B.C.'s "Huainan Wanbi Shu": "Cutting ice makes a circle, lifting it to the sun, and taking its shadow to bear the fire is born."

Fire and water are incompatible, but after being made into an ice lens, it can be used to make fire, which cannot but be said to be the ingenious creation of the ancients. The fire bead also uses the convex lens focusing principle to make fire to the sun. "Xiangzu Notes" said, "There are yang sui beads in the Great Food Country (now Arabia), and Zhao Tuo makes people steal back to Panyu."

The Book of the New Tang Dynasty also records that "the Bori (now Bali, Indonesia) have many fire beads, and the Japanese and Chinese pearls are Ai beads, and the fire comes out." "In the fourth year of Tang Zhenguan (630 AD), Linyi (in present-day south-central Vietnam) sent an envoy to offer fire beads to the Tang Dynasty.

The ancients knew how to use the sun to make fire very early, that is, in the cold winter, the ice was made into a lens, and the concentrated solar energy was used to ignite the wormwood to make a fire.

In ancient times, time referred to the shadow of sunlight, because at that time they used sundials to keep time.

Time refers to time, and the second emptiness is probably timed by a sundial.

There are many ancient timekeeping tools, but the one that used light and the shadow of light to calculate time was most likely a sundial.

Restore the ancient "sundial":

Use a random piece of material to make a disc. A straight and slender iron wire is fixed in the center of the disc, perpendicular to the disc surface.

Divide the disc with 24 equal parts, 36 equal parts, etc.

On a clear night, outside, aim the wire at the "North Star" and fix it. Your "sundial" is made and installed.

The next day, the sun's rays will cast a thin wire shadow on your sundial. The shortest moment of the shadow is at noon.

For the use of sundials, please refer to the introduction materials on sundials.

Sun Clock: The earliest time was measured by the sun, and day and night were a day.

Light and shadow clock: The length of the shadow of the wooden stick in the sun is changed, and the scale is marked to reflect the change of time.

Leakage clock: Calculate the time by using the number of water droplets and sand leaks. ··

Sunshine or sun. Shadow with a light stick.