Caste your mind back to school supplies. Along with the usual notebooks and pencils, at some point geometry or math sets were added to the list. I still have the metal box my first set came in although some of the contents are missing. The British Helix company that made it is still around today. They were making rulers and other educational equipment for awhile when in 1912 founder Frank Shaw hit upon the idea of combining a number of their products together to make a mathematical set for students. The set included a compass, protractor, set-square, ruler, pencil and eraser; much the same as their current product although now the protractor, set-square, and ruler are plastic, not wood.
While all of these tools go back a long way, rulers (also called straightedges or line gauges) are probably the first measuring instruments. One found in India dates to around 4,500 years from the present. Earliest examples were made from ivory and bone but wood, metal, and plastic now rule the day. The markings on rulers are called hash marks and generally (at least in Canada) are marked on one side with the metric system and imperial on the other.
Not everything is straight though so for circles or arcs we need a compass. It’s a metal V-shaped tool that has a holder for a pencil on one end and a point on the other with an adjustable hinge in the middle that is held steady with a screw. Similar to a compass but with points on both ends is a divider, used to compare lengths. Both date back to at least ancient Rome. Somewhere along the road of life my divider and I parted ways.
The two triangles included in these sets (90-45-45 degree angle triangle and 30-60-90 degree triangle) are also called set-squares. They make it easier to draw angles, as well as perpendicular and parallel lines.
The half circle is a protractor. They are marked from 0 degree to 180 degrees in order to measure angles. Nobody knows who invented it (some speculate ancient Egyptians) but certainly a version was already in use during the 13th century, where it was used with an astronomical device. By the 18th century it was common enough to be mentioned in geometry textbooks.
Math was never my favourite subject but in a world that can seem so divisive I see the appeal in the certainty and logic of mathematics, not to mention the fun of getting a little set of geometry tools in a tin box.
If geometry sets were people, they would be math nerds with a sense of history (as well as a sense of humour). They all love pie and make sure everyone gets an equal piece.