Definition of the word spirit level

The term "spirit level" originated in the 1790s in England, during the Industrial Revolution. At that time, glass experts created a new type of glass called "spirit" as a byproduct of distilled alcohol production. This glass was thinner and more transparent than traditional glass and became popular in scientific and engineering applications due to its high precision. One such application was the development of the "spirit level," a tool used to check if a surface is level, or horizontally flat. The spirit level consisted of a small glass vial filled with a liquid (often mixed with spirit, hence the name) with a bubble inside that floated in the center of the vial. As the vial was placed on the surface to be tested, the bubble remained at the center, indicating a perfectly level surface. The significant advantage of the spirit level over competing leveling devices like plumb bobs and beam levels was its accuracy and ease of use, as it provided a visual indicator in real time. The spirit level soon became widely used and established itself as a fundamental tool in construction and engineering fields. Thus, the name "spirit level" remained associated with the tool, despite the discontinuation of spirit usage in the product.