VICTOR DE SCHWANBERG / SCIENCE PHOTO LIBRARY VICTOR DE SCHWANBERG / SCIENCE PHOTO LIBRARY
Spirit levels. Close-up of two spirit levels combined in the same piece of equipment. A spirit level is used to measure how level a surface is. It consists of a tube filled with a coloured fluid and a single air bubble. When the spirit level is placed on an even, flat surface, the air bubble will remain between the two vertical lines in the centre of the tube (as here). However, if the surface slopes, the air bubble will move to the left or right of the markings. The type of spirit level shown here can be used to measure both horizontal and vertical surfaces using the same piece of equipment.
Model release not required. Property release not required.