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Why do we need compasses? The history of its origin and practical application.

The compass is an ancient, but still actual invention of mankind. This subject is interesting because its invention served purely scientific purposes. The compasses could not be used for hunting, like bow and arrows, for movement, like a wheel, for cooking food and scaring animals like fire. Only in the Bronze Age did it become necessary to draw right circles on the ground. So, with attempts to draw, measure and isolate this or that circle, an understanding has come of what the compass is for and how to work with it.

The legend of the appearance of the compass

Tradition prescribes the invention of a circular to the legendary inventor of the nephew of the famous Daedalus - Talos. Talos lived in Athens. Already at the age of 12 he invented a potter's wheel with which it was possible to make various utensils. Walking along the seashore, Talos lifted the skeleton of the fish, and this pushed him to the idea of another invention - a saw. By connecting two identical sticks to the hinge, Talos coined the compasses. Daedalus envied the genius of his nephew and once on a walk pushed Talos from the city rampart.

Scientific hypothesis

There is another, more scientific hypothesis that explains why a compass is needed , as this thing appeared among the objects of ancient people. In order to outline the circle, they took a peg and a rope. A rope or a piece of chalk was attached to the rope, and thus a circle was drawn. Later, the rope was replaced with a thin twig or plank. This made it possible to delineate circles only of a given radius. Finally, and this problem was solved - to one of the plates attached another and fastened them together. Thus, the first compass was obtained.

Structure of the compass

The principle of the circulation and its structure remained unchanged for several hundred years. Modern technology only made this device more convenient to use. In our time, the compass consists of such parts:

- the holder. The uppermost part of the compass. The main purpose of the holder is to prevent the hand from sliding during the drawing. Therefore, the holders are roughened or with special notches for the fingers;

- Rods. This is the main working part of the compass, its "legs." Professional draftsmen prefer circuses, in which rods are made of high-strength metals. This provides a firmness of the line and a minimum error when using the device. And why do we need a compass with plastic or wooden bars? In children's and school instruments, high accuracy is not required, therefore such compasses can be made of plastic;

- the needle. It should be very strong and sharp, so as to fix the compass at the point of reference as much as possible and reduce the probability of the tool sliding off the drawing;

- Nozzles. Usually, the nozzles are slate rods of different rigidity. The draftsman chooses the hardness of the lead depending on the type of work performed.

Using a compass in geometry

On the answer to the question of why the compasses are needed, no one thinks about it for long. This subject is familiar even to schoolchildren of lower grades. The main thing for which you need a compass is to draw circles of different sizes. Older students already know that circulations not only draw circles, but also solve many different geometric problems.

For example, dividing a segment into two equal parts without drawing tools is very difficult. Using the compasses, you can divide the segment into two parts that are exactly the same in length. As can be seen, for such an operation, it is necessary to make the points denoting the ends of the segment to be the centers of intersecting circles. Through the intersection points of these circles along the chord we draw a line. The intersection point of the line and the given segment will divide this segment exactly in half.

Here is another example of what a compass is for. Let's say that the sides of the triangle that you want to build on paper are given. "By eye" it is impossible to determine the right angles that such a triangle will have. With the help of the compass, it is very easy to build a figure. We take a segment equal to one of the sides of the triangle. From the ends of the segment we draw circles, the radius of each of which is equal to the specified length of the side of the triangle. The intersections of the circles become the angles of the triangle we need.

Now you have an idea of why a pair of compasses is needed. The pictures presented above illustrate its use.

Use of a measuring loop

Since ancient times, the compass has expanded the scope of its application. For example, this tool is found without a lead or a pencil - on both legs there are sharp needles. You can ask why you need a compass without a lead? Any engineer will say that this is a compass measuring instrument. It is not intended for drawing circles and ellipses, but is available in each cut-off. What is the purpose of the compass meter? With it, you can quickly and accurately measure the same distances in the drawing or mark up the drawing with almost invisible scratches on the paper.

Use of compass by surveyors

They use compasses and surveyors. Only they have it big, and the distance between its bars is strictly defined - usually it's one meter. Stepping along with such a compass, the surveyor can accurately determine the size of the plot of land, because with each step of the surveyor such a compass measures one meter of the square.

These examples only give a small degree to the concept of what a compass is for. The answers, deeper and more detailed, can be offered by mathematicians, geologists, engineers, builders and people of other professions.

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