In bricklaying, the terms “plummet” and “bob” refer to a tool used to determine if a vertical line is straight and true. The tool consists of a weight (the “plummet”) suspended from a string or cord (the “bob”) that is attached to the top of the wall or structure being built. The plummet is typically a pointed metal or lead weight.
To use a plummet in bricklaying, the bricklayer would attach the string to the top of the wall or structure and allow the plummet to hang freely. The plummet should come to rest in a position that is directly above the starting point on the ground, indicating that the line is perfectly vertical. The bricklayer can then use the line as a guide when laying bricks or building the wall.
The plummet tool is useful in ensuring that walls are straight and true, which is important for both aesthetic and structural reasons. It can also be used to check the alignment of other structures, such as columns or posts.