Episode 1.2: Stairway to Even (Script)

Hi. I’m Keith Decent and this is From the Ground Up. A podcast about how we make what we make, the materials, the tools, and the stories behind the things we build. Picture France in the 17th Century. The Old Masters of the Renaissance are gone, the streets and museums and palaces are drenched in their creativity. The absolute appreciation they showed for the world and for humanity has inspired a deep desire to better understand it all. The first sparks of the Age of Enlightenment are starting to form. Philosophers and amateur scientists abound. Not only in France, but in all parts of the Western World. The King, Louis 14th, is in the early years of what will be the longest reign of any European Monarch in history. As he consolidates and strengthens his power, Louis also gathers artists, scientists, mathematicians, and most of the country’s royalty to join him at his grand Palace of Versailles. The palace itself used to be a sort of hunting lodge built by Louis’ father, and is being expanded to fit it’s new role as the seat of power and culture for the French Empire. If you could peer into the tool chests and totes of the carpenters and masons laboring at the palace, most of the items inside would look pretty familiar to a modern tradesperson. Hammers, chisels, planes, and saws are all there. Among the measuring tools, the dividers, angle finders, and rulers, however, would sit a truly ancient device, the plum level. Let’s go back, very far back, to Ancient Egypt. You are a stonemason, and you’ve been tasked with building a pyramid. One thing everyone knows about pyramids, is that they have to be level to the ground. You can’t very well have one stone sitting at an odd angle, it’ll just throw the whole thing off and the Pharoah will just make you, and probably the next 7 generations of your family, do the whole thing over again. So you need a tool that will make sure the top and bottom of every massive stone is dead even and level. You fashion a tool to help you out. It needs to be a right angle, exactly 90 degrees. No one has invented the protractor yet, so you use the stars and the horizon, and can gauge that angle perfectly. You construct the tool. It’s essentially a right angle with two legs the same length with a horizontal brace running between them. You don’t know what the letter A looks like, but you’ve essentially just made one out of wood. From the apex of the right angle, you hang a string with a stone weight, or plumb line and bob. You mark the center of the brace and you can now find out if any surface is level. You’ve created a tool that will remain in use, and largely unchanged for thousands of years. In a couple of millennia, the Romans will use your tool to build their grand structures and engineering marvels. They will add a few features, connecting two of the devices by a beam that replaces one leg, in order to measure longer sections of their work. Also, they will add a trough to the top of the beam, so they can fill it with water and check it’s level on windy days when the plumb lines won’t work. They will call it a Chorobates. A few hundred years later, craftsmen in the middle ages will modify your tool once again. Taking the same concept, they will take a long, flat board, and add a semicircular extension to the top, from which their plumb line and bob will hang. This will give them the added ability to measure many different angles with great accuracy. And back in Early Modern France, at the construction site in Versailles, these varied tools will still be used. However, in perhaps a few very special cases carried proudly by a few forward thinking tradesmen, there is something new. The spirit Level. Melchisedech Thevenot can be credited for a great many accomplishments. He was part of a wealthy class of French Royal Office Holders. He and his family were not royalty themselves, but were as close as one can get before having a hereditary title. His upbringing afforded him a great many opportunities for advancing his knowledge of the world and he took advantage of seemingly every one.

His CV reads like that of a man who lived 3 lifetimes. He spoke English, Greek, Latin, Hebrew, Arabic, and Turkish, and reportedly a few other languages. In his lifetime he was an author, later writing and publishing a book titled “The Art of Swimming,” which popularized the breaststroke and was a favorite of Benjamin Franklin. He was a cartographer, having produced and published some of the earliest and most detailed maps of certain parts of the Middle East. He was an avid traveler and served time as a diplomat to both Genoa and Rome. He was an amateur scientist, studying astronomy, magnetism, anatomy, medicine, and physics. And he was also a patron of the sciences, partaking in and funding studies that led to breakthroughs in understanding how embryos are fertilized in humans and animals. Because of Thevenot’s expertise on the lands east of Europe he was deemed an “orientalist,” a title more apt than ever could have been foreseen for the man who would revolutionize the way we level our work.

On February 2, 1661 Melchisedech Thevenot wrote a letter to his longtime friend and fellow scientist, Christiaan Huygens, detailing a new invention. Thevenot had taken a small vial, filled it most of the way with alcohol, fitted it into a stone ruler, and attached a viewing lens. Its operation was such that the bubble of air in the vial would move back and forth as the ruler was tilted, resting in the marked center when it’s held level. If this sounds familiar, that’s because it’s very nearly exactly the same tool still in use today by people all over the world. Many enhancements were made in the 1920s and 30s by Harry Zeimann, founder of the Empire Level Manufacturing Corporation, bringing the device into the modern industrial era with his invention of the mono vial. The rulers are no longer stone, but are typically plastic or aluminum, and the alcohol or oil, chosen for its viscosity and lower surface tension, is often tinted a yellowish color for increased visibility in the tubes, now primarily made of acrylic, though masons still use more scratch-resistant glass. But this clever device is readily purchasable, right now, in any hardware store in a form largely unchanged since the 17th century. One of the reasons for the spirit level’s longevity, aside from its versatility and elegance, is the fact that it can be miniaturized. They can be manufactured in very small sizes and still be readable, a task the plumb level had no hopes of ever achieving. Today it is embedded in a wide variety of tools and other objects. You may have seen one in the back of your battery operated drill, placed in the hilt of a combination square, in the base of a measuring tape, or even in the side of a mechanical pencil. And what did Thevenot do with his brilliant invention? He gave it away. He circulated his idea among colleagues, including fellow polymath Robert Hooke in London, and famed Florentine Mathematician and scientist, Vincenzo Viviani. Despite his best efforts to spread the word about his new tool, it never really caught on until the early 18th century, despite being well known among his colleagues and contemporaries.

If you think that Thevenot would have fit in perfectly with Louis XIV and his court at Versailles, you’d be right. The King himself thought so, too, and after Thevenot helped inspire the creation of the French Royal Academy of Science, Louis hired him to be his royal librarian. He remained a devoted scientist and correspondent, writing letters to and collaborating with other scientific minds up until his death at the age of 72, in 1692. Since Thevenot’s death more than a few enterprising souls have made improvements to his design. The Fell, “All-Way” level is what’s called a bulls-eye level, invented by William B Fell, is a domed vial, with the indicator for level on the top, and is read from above. It’s made for leveling flat surfaces on both an x and a y axis, and is invaluable for aligning tool beds. This device, invented just prior to World War II, was so accurate that it was restricted from export, as it was a valuable asset to American Manufacturing and therefore the war effort itself.

Aside from the aforementioned mono vial, Zeimann also invented the torpedo level, a shorter device for tight spaces, the magnetic level for plumbers to attach onto pipes, and the snap-in interchangeable vials, for easy replacement of the most delicate part of the tool. These changes and modifications would not have been possible without the collaborative spirit and the free exchange of ideas so cherished by the great thinkers of the 17th century.. They realized they could unravel the mysteries of the earth faster and understand more about our world than anyone ever before in human history, simply by pooling their talents and knowledge together. Whether corresponding by mail, meeting at a colleagues home, or founding a national academy of science, they brought the western world into the Age of Enlightenment and onward to the Industrial Revolution. Mathematicians, Politicians, Scientists, philosophers, artists, kings and librarians, working hand in hand, creating great works that we can still utilize and learn from in our modern lives. From the Ground Up is an ongoing experiment, and it is now and will always be available free of charge. If you’d like to support this podcast, please visit to learn more about the show and how you can help out. Until next time, this is Keith Decent saying, later makers.