# how were straight lines made?

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in elementary school, my teachers would say, “if you need a straight line use a ruler,” but how did they get a ruler to be straight? it must have come from a machine or something, but how did people get the first one?

one way I’m imagining it is if you stretch out a string taut you can get a straight line, but how was this applied to everything else that uses straight lines?

is there something in nature that is perfectly straight?

In: Engineering

Take a string, tie it to two stick. Pull the sticks apart, string becomes taut. You now have a straight line. You can use shorter lengths of rope to decrease your margin of error.

Source: We still run string lines today.

The simple answer to where straight lines come from is that, if you take three stones and alternate rubbing them against each other, eventually you will get three perfectly flat surfaces. Join two points on one surface, you will get a straight line. Use the stones as a reference for building the first ruler.

Here is a link to a GREAT video about exactly where measurement came from, even asks the question about straight lines. Chanel is called Machine Thinking

https://youtu.be/gNRnrn5DE58

Water levels are effectively straight over a human scale.

To *create* a straight edge tool, you simply mill and shave away at things multiple things compared to each other until they are straight. Imagine you have 2 planks. You place 1 and 2 against each other, and since neither is straight, there will be gaps. You note the high points which create these gaps, and cut them down with sanding and planing. You repeat this process until the two boards match.

You can also just fold a piece of paper in half.

If you enjoy reading, check out The Perfectionists by Simon Winchester. He explores the earliest (and most crude) measurements of precision up through the achievements of millionths of a meter and a second in the contemporary age of GPS and aerospace. A fascinating and entertaining read!

Use gravity to help you make a straight line if you want to see such things in nature. Tie a string around a stone; hang the stone over a nearby branch; gravity gives you a straight line.