Measuring Rulers - History, Usage and Types of Rulers

A ruler is an instrument that can measure distances or draw straight lines in printing, geometry, technical drawing, and many other things.

Throughout history, humans usually take their parts of the body as measuring units. Such units are hand, foot, or cubit. The metric system was invented in France for easier measuring, and by the end of the 18th century, most countries adopted it. People have been using things to help them measure something for more than four thousand years.

The first ruler was a measuring rod made of copper alloy, dating from 2650 BC. German assyriologist Eckhard Unger found that measuring rod. In 1500 BC, ivory rulers were used by the Indus Valley Civilization. Some findings in Lothal proved that a ruler was calibrated to 1.6 millimeters, and it was 4400 years old. Mohenjo-Daro ruler has accuracy within 0.13 millimeters. Anton Ullrich invented the first folding ruler, and the first flexible ruler was made in 1902.

Types of Rulers

Rulers come in different shapes, sizes, and materials. Some of that materials are plastic, wood, and metal. Metal, as a stronger material, is often used for workshop rulers. Rulers that are used for office work are usually made of wood. Rulers can be made in different sizes. The usual size for a desk ruler is 30 cm. Longer ruler size is 45 cm. Some small rulers can fit in a pocket, and carpenter rulers can be folded in a zig-zag shape. For larger measuring distances, yardsticks (1 yard) and meter sticks (1 meter) are in use, but today, it is increasingly replaced by tape measure and laser rangefinders.

Three main usages of desk rulers are to measure, to draw lines, and as a straight guide for cutting with a sharp blade.

A line gauge ruler is a ruler that is mostly used in the printing industry. Units on that kind of ruler are millimeters, inches, agate, picas, and points.

One of the specialized rulers is a shrinkage ruler. That type of ruler is designed for making a wooden mold for a metal slightly bigger than the finished product because of the shrinkage rate of the metal.

Rulers don't always measure straight lines. Sometimes, like in the tailoring industry, it is needed to measure a person's waist measurements, for example, so there is a folding instrument for that purpose.

There is also a virtual ruler, ruler software, or screen rulers. It can be used to measure pixels on computers or mobile phones. Contrary to that, there is also a ruler for drawing curved lines. That kind of ruler is known as a French curve. There is also a flexible device known as a flat spline or flexible curve, which can be bent into a desirable shape.