compass - an ancient but still actual invention of mankind.This subject is interesting because his invention served purely scientific purposes.Compasses can not be used for hunting, as a bow and arrows to move, like a wheel, for cooking and scaring away animals like fire.Only in the Bronze Age there was a need to plot the right circle on the ground.Thus, attempts to draw, measure and isolate a particular circle come to understand why we need a compass and how to use it.
legend about the appearance of the compass
Tradition dictates invention compasses legendary inventor of the famous nephew of Daedalus - Talos.Talos lived in Athens.Already in the 12 years he invented the potter's wheel, with which it was possible to produce a variety of dishes.Taking a walk along the seashore, Talos raised fish skeleton, and it led him to the idea of another invention - a saw.Connected by a hinge, two identical sticks, Talos invented the compass.Daedalus envied the genius of his nephew, and once on a walk pushed Talos with the city wall.
scientific hypothesis
There is another, more scientific hypothesis, which explains why there is a compass, how did this thing among the subjects of ancient people.In order to outline the circle, took a peg and rope.Attached to a rope or a piece of chalk coal, and thus draws a circle.Later replaced by a thin rope or a sprig of plaque.This allowed to delineate a given radius of the circle only, Finally, and this problem has been solved - plaque attached to one another and hold them together.So to get the first and compasses.
structure compass
The principle of compass and its structure remained unchanged for hundreds of years.Modern technologies have made only this device more convenient to use.In our time, the compass is made up of these parts:
- holder.The top of the compass.The main purpose of the holder - to prevent skidding when performing a drawing hand.Therefore, holders and make rough or with special recesses for the fingers;
- rod.This is the main working part of a compass, his "feet."Professional detailers prefer compasses in which rods are made of high-strength metals.This provides a line of firmness and minimal error when using the device.And why we need a compass with plastic or wooden rods?In children and school instruments high precision is not required, so such compasses can be made of plastic;
- needle.There must be a very strong and sharp to make the most tightly fasten the compass at the reference point and reduce the chances of slipping drawing tool;
- nozzle.Typically, nozzles perform slate rods of different stiffness.Draftsman picks up the stiffness of the lead depends on the type of work performed.
use a compass in geometry
Over the answer to the question of why we need a compass, no one thinks for a long time.This item is familiar even to schoolchildren.The main thing is why we need a compass - draw circles of various sizes.Students older already know that not only the compass draw a circle, but also solve a lot of different geometric problems.
For example, to divide the segment into two equal parts without drawing tools very difficult.Using a compass, a segment can be divided into two completely equal length parts.As can be seen, for such an operation is necessary to point indicating the ends of the segment, became the center of intersecting circles.Through the point of intersection of these circles along the chord line of conduct.The intersection point of the line segment and the specified share this piece exactly in half.
Here is another example of why we need a compass.For example, a given side of the triangle, you want to build on the paper."In the eyes" is impossible to determine the correct angles, which will have a triangle.With the help of a compass to construct a figure very easily.Take a section of one of the equal sides of the triangle.Of all pigtail circle, the radius of each of which is equal to the predetermined length of the side of the triangle.The point of intersection of the circles, and we will correct angles of the triangle.
Now you have an idea of why we need a compass.Images shown above illustrate its use.
use compass -izmeritelya
Since ancient times, the compass has expanded its scope of application.For example, this tool is found at all without the lead or pencil - on both his legs -ostrye needle.One might ask why we need a compass, without the lead?Any engineer will tell you that it -tsirkul-meter.It is not intended for drawing circles and ellipses, but there is in each of drawing.Why the need for a compass meter?With it you can quickly and accurately measure the same distance on the drawing or mark up drawing using almost invisible scratches on paper.
use compass surveyors
Use a compass and surveyors.Only they have it large, and the distance between its rods strictly defined - usually one meter.Walking along with a compass, the surveyor can accurately determine the size of the land, because with each step surveyor a compass measures the per meter square.
These examples are only a small degree of give an idea of why we need a compass.Answers, deeper and more detailed, can offer mathematics, geologists, engineers, builders and people of other professions.
