Sundial

Sundial

Surely you have ever seen a sundial and you don't really know how to use it. It is a type of instrument that was created to measure the passage of time through the movement of the sun. The graphical representation of this type of clock will be made from the shadow produced by a stiletto known by the name of style or gnomon. In order to know how time is passing throughout the day, the presentation is made on a table in which different marks are recorded. The shadow of the stylet is named after the sun and is collected on the surface that is generally flat or cylindrical.

In this article we are going to tell you all the characteristics and the history of the origin of the sundial.

History of the sundial

This type of watch is also known by the name of the solar dial. It was not the Greeks who began to treat this subject, although normally this type of instrument is devised by them. In this case, we find the Egyptians who, back in the XNUMXth century BC, had already begun to divide the night and the day into equal parts. The division of day and night into equal parts began to be carried out through the appearance of certain stars. This is how they were able to think and design different ways to know the passage of time.

The problem with this form is that it was not portable. Some studies reflect that the pyramids of Egypt were already oriented in a certain way to be able to know the passage of time. Furthermore, the obelisks designed during this time also fulfilled this idea of ​​solar measurement. Later, centuries later, in the Greek and Roman times, there are many documents that reveal the evidence of the manufacture of the sundial.

How does it work

The sundial is based mainly on the shadow that the stylus casts on the surface. Since the sun has a different orientation as the earth exerts its rotational movement, the different hours of the day can be captured on a surface and the stylus will project a shadow according to the time of day we are in.

You have to think about the apparent movement of the sun on any given day. The sun rises in the east, passes through the south at noon, and sets in the west. Noon is considered at 12 in the morning. The supposed movement of the sun throughout this period is a constant movement. It disappears in the west and travels east again, but as it does so, it is night for us. In this way we see that the entire path of the sun has an angle of 360 degrees in about 24 hours. The speed at which it is moving steadily is 15 sexagesimal degrees per hour.

Once we know this, we must think that the sun makes the apparent movement by turning around the axis of the earth. If we want to know what time it is according to the movement of the sun, we must have a representation as faithful as possible to the rotational movement of the earth. The style of our sundial must match the tilt of the earth's axis. This means that the inclination that this style must have with respect to the vertical of the place where we are must be equal to the latitude in which we are.

How to make a sundial

We are going to talk about the necessary guidelines to be able to make a sundial as simple as possible. In this case, the making of the sundial begins with the placement of the stylus or style of the direction of the earth's axis. That is, approximately dWe must place the style in the north-south direction. To ensure that this style is located in the correct position, we must ensure the latitude of the place where we are. The latitude of the area where we live can be learned from a coordinate map.

Once we have placed the stylus we already have our latitude determined. Thanks to this latitude we know the inclination with which we must place the stylus. Now we just need to draw a quadrant where the shadow is reflected and mark the hours of the day. In the quadrant or board we will place in one way or another the type of sundial that we want to build. Here you have to give free rein to the imagination. Each type of sundial will have a different design according to our tastes.

Types of sundial

We are going to analyze what are the different types of sundial that exist. These types will vary based on the orientation of your quadrant. We have the following types:

  • Equatorial sundials: are those that have the quadrant placed on a plane parallel to the terrestrial equator. Here we have the well defined stylet tilt and it is quite easy to place this plane. We just have to know that they have an inclination of 90 degrees on the horizontal.
  • Are horizontal clocks: are those watches that have a dial placed perpendicular to the vertical of the place. They are easy to construct and interpret since the marked extends north and the quadrant will not be marked all hours of the day.
  • Vertical sundials: They are a type of model in which the style is oriented in the north-south direction. The dial shows the hours of the day and the dial is vertical. Keep in mind that we can orient the quadrant to the north or south, to the east or west.
  • Other types of sundialThere are other types of sundials that are less common but can be just as effective. Here we find the pastor's watch that is portable, vertical and small. These clocks receive this name since they were used by shepherds to know the time of day when they were to take the cattle to graze. Another type of sundial is the diptych clock. This watch stands out for having two quadrants divided into one vertical and the other horizontal. These two quadrants are linked together by an axis. In this case, we find that the style is a thread that is left thought when we place both quadrants perpendicular. Normally they need a compass to be able to mark the hours well.

I hope that with this information you can learn more about the sundial and its characteristics.


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  1.   Robert Count Bouza said

    The Covelo sundial was made by Roberto Conde in 2000 and not long…working for the Covelo city council and being mayor D.Jose Costa, who generously offered me the opportunity to expand artistically and gnomically and that was the humble result .