Compass (drawing tool)

A compass is a tool for drawing circles.

It has two legs joined at the top.

One leg has a sharp spike. This spike stays in the middle.

The other leg holds a pencil.

You can move the legs to change the size. This makes the circle wide or thin. Some tools have a beam for huge circles.

People use them for math and maps. You can also use them to mark distances. They help people draw very straight lines.

It is a great tool for being precise.

A compass is a tool for drawing circles or arcs.

It is often called a pair of compasses. Most compasses are made of metal or plastic. They have two legs joined by a hinge.

One leg is a steady leg. It has a needle point to anchor the tool. The other leg is an adjustable leg. This leg holds a pencil, pen, or lead.

You can change the size of a circle. You do this by changing the angle between the legs. This change sets the radius, which is the distance from the center.

To draw, push the spike into the paper. Then move the pencil leg around the center. Some people move the paper instead.

Compasses can also work as dividers. Dividers have two spikes instead of a pencil. You can use them to mark distances on a map. Some tools are built for very large circles. These use a long beam. We call these beam compasses.

Today, computers do much of this work. We still use compasses to learn geometry.

A compass is a handy tool for drawing perfect circles or arcs.

People also call it a pair of compasses. This tool helps with math, drafting, and navigation. Before computers, people used these tools for manual drafting. Now, computers do much of that work. We still use physical compasses to teach geometry and technical drawing.

Most compasses are made of plastic or metal. They have two legs connected by a hinge. One leg is a steady leg with a needle point. This spike anchors the tool into the paper. The other leg is adjustable to change the circle size. This leg holds a pencil, a pen, or lead.

To draw, you push the spike into the paper. Then, you move the pencil leg around the center. You can change the radius by adjusting the angle of the legs. Some people move the paper instead of the tool. A hinge screw holds the legs in place. A tighter screw makes the tool more accurate. High-quality versions may even have a small wheel for fine tuning.

There are many different kinds of compasses. A beam compass uses a long wooden or brass beam. It is used for drawing very large circles.

Some tools are called dividers because they have two spikes. These are used to measure distances on a map. Other tools, like ellipse compasses, draw different shapes. Carpenters might use a scribe-compass to trace a line.

History shows us how important these tools are. Euclid used a special tool called a collapsing compass in his work. He wrote about this in Book I of his book, the Elements. He proved a collapsing compass could do anything a real one can. In 1611, the poet John Donne used a compass as a symbol. Today, the compass remains a symbol of precision and careful design.

A compass, often called a pair of compasses, is a technical drawing instrument. It is used to inscribe circles or arcs onto a surface.

These tools are essential in mathematics, drafting, and navigation. Before computers became common, manual drafting relied heavily on these physical instruments. Today, computer-aided design programs handle many drafting tasks. However, physical compasses remain important for teaching geometry and technical drawing. They serve a vital didactic purpose in classrooms worldwide.

Most compasses consist of two legs joined by a hinge. This hinge allows the user to adjust the radius, which is the distance from the center to the edge.

One leg is known as the steady leg. This leg features a needle point that acts as an anchor. The other leg is the adjustable leg. It holds the drawing tool, such as a pencil, a pen, or a piece of lead. The user can change the size of the circle by altering the angle between these two legs.

Precision is a key feature of a high-quality compass. The hinge is controlled by a screw that holds the legs in position. A tighter hinge-screw leads to more accurate performance. Some advanced models are called "Spring-Bow Compasses." These high-quality versions are made of plated metal. They include a small, serrated wheel for fine adjustments. They may also feature a spring that encompasses the hinge to help maintain stability.

To draw a circle, the user must follow a specific process. First, the needle point of the steady leg is pushed into the paper. This point establishes the center of the circle. Next, the drawing tool on the adjustable leg is placed on the surface. The user then moves the pencil around the center while keeping the leg angle constant. Some people find it easier to hold the compass still and rotate the paper instead.

There are several specialized variants of the compass designed for different tasks. A beam compass uses a long wooden or brass beam with sliding sockets. This tool is used to draw circles much larger than a regular compass can manage.

Another type is the dividing compass, or dividers. These have two spikes instead of a pencil. They are used to mark distances on maps. By measuring how many times the spikes fit between two points, a user can calculate the distance.

Other specialized tools exist for specific trades and shapes. Scribe-compasses are used by carpenters to trace lines or bisect angles. Some versions use a wing nut to tighten the pencil and lock the distance. Reduction compasses, or proportional dividers, are used to enlarge or reduce patterns while keeping angles the same. There are even ellipse drawing compasses designed specifically for that shape.

The history of the compass is tied to the foundations of geometry. Euclid discussed an abstract version called a "collapsing compass" in his work, *The Elements*. A collapsing compass is a theoretical tool that disappears after drawing a circle. It cannot be moved to draw another circle of the same size. However, Euclid proved in his second proposition of Book I that such a tool could still transfer distances. This proved that a collapsing compass could perform any task a real compass could do.

Beyond math, the compass holds significant symbolic value. It is often used as a symbol of precision and discernment. This is why it appears in various logos and icons. For example, it is part of the Freemasons' Square and Compasses. Even literature has embraced the tool. In 1611, the English poet John Donne used the compass as a conceit in his poem "A Valediction: Forbidding Mourning."