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Silly titles aside, we all know the plumb bob is our friend; there is no doubt about that. This tool has been used for at least the last 4,000 years, probably longer, to ensure that our buildings stand true. But where exactly did this ancient tool originate, and how can something so old still be valued as much as it is today?
The Birth of the Plumb Bob
The need to keep a structure true has been around since buildings themselves. If a building, joist, or beam is even just a little bit off, it can completely disrupt the structural integrity of the entire thing. That’s why early builders noticed extremely early on that they needed an instrument that would tell them whether or not a part of the structure is true with another.
This necessity forced the use of a tool that would allow for builders to ensure that their structure was sound. Enter: the plumb bob. The plumb bob is really one of the simplest tools in the building world. Really. You can make one right now. Just grab a rock, tie a piece of string to it, and fix the other end of the string to a straight piece of wood. There you go. Now you’ve got your own plumb bob. Go around your home or office, seeing if all of your edges are straight, and if anyone asks what you’re doing, just say ‘Science.’
The ancient Egyptians were some of the earliest users of this tool, although there were more than likely many more before them that used some sort of leveling device. The use of the plumb bob allowed them to build structures like the Pyramids of Giza, the Temple of Horus, and the Luxor Temple. Now, granted, the material that these buildings were constructed with contribute greatly to their longevity, as well as the climate of Egypt in general, but the use of the plumb bob helped the Egyptians create structures that would last hundreds of generations, and show no sign of going away any time soon.
The Evolution of the Plumb Bob
Plumbs were originally made with stone, as stated earlier. But as time went on and greater precision and accuracy became necessary, the crude stones and rocks were replaced with pointed, metal weights. These weights were originally made out of lead. Now, if you’re up on your Latin, you’ll know that the Latin word for lead is ‘plumbum,’ hence leads atomic symbol, ‘Pb.’ The heavier, pointed weights allowed for greater accuracy with the tool, whereas a stone just gives you a rough estimate of level.
As the plumb itself evolved, so did the methods in which to use it. Plumbs were usually fixed to right triangles. This piece of equipment, called a plumb square, was used to make sure that two edges were straight.
The Modern Plumb Bob
The plumb bob’s rule at the top of the leveling chain lasted for a very long time. Even up to the early 20th century, workers on skyscrapers would hang massive plumb bobs through elevator shafts to make sure that their building was standing straight. But, all that was about to change.
The spirit level was no new piece of technology by any means. Bubble levels had been in use since their invention in the 1600s, but the rise of cheaper materials like steel gave the average consumer easy access to a much more accurate, and let’s be honest, less time consuming method of maintaining accuracy.
The spirit level (called so because the original levels were made by suspending one air bubble in alcohol) was originally invented for use in telescopes and then used in surveying. But it was not until 1939 that the first spirit level was produced for the masses by William B. Fell. These spirit levels gave carpenters, builders, and everyone in between the opportunity to make sure that every single surface in the building process was level, from ground to foundation, and frame to ceiling.
Just because the plumb bob has stepped down from its throne as king of the level world doesn’t mean that they aren’t still in use. Plumbs can still be found in the tallest skyscrapers, the deepest mine shafts, and the longest bridges. We even have one here on the wall in our survey department. It’s a large wall-mounted plumb that we’ve nicknamed ‘Bob.’ So the next time that you see a plumb, remember that there are over 4,000 years of history behind this once-great king of the leveling world.
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Sources:
http://www.antiquetools.co.uk/articles/bob.htm
http://www.surveyhistory.org/egyptian_surveying_tools1.htm
http://www.bobvila.com/articles/495-the-plumb-bob/#.VVX5ZflVhBc
http://www.britannica.com/EBchecked/topic/560417/spirit-level