A torpedo level is a spirit level designed for use in tight spaces. Place the level on the surface of the object for which you want to find the true horizontal (the “horizon”). Make sure the spirit tube runs parallel to the object. Allow the bubble to float to the top of the spirit tube. Put your eyes at level with the spirit tube. Anyone who regularly works on construction sites or has carpentry projects at home can make good use of the torpedo level. It is not difficult to use this type of level. The process used to check a surface for plumb, level, or a 45-degree angle is similar to the methods used for other types of spirit levels. The spirit, or bubble, level, a sealed glass tube containing alcohol and an air bubble, was invented in 1661. It was first used on telescopes and later on surveying instruments, but it did not become a carpenter's tool.