Plumbs and Levels
Tools used to test for vertical and horizontal have always worked on the same principle. The essential features were a heavy bob and line. Egyptian levels used the bob and line suspended from the apex of an A-shaped wooden frame. This type was in general use up to the Middle Ages. A later form, common until the mid nineteenth century, was a short plumb rule and bob set at right angles to a straight edge.
Levels had been known and used in surveying and navigating instruments before 1800, but they were adopted by carpenters and others at about that time. They are now also used in plumb rules. The main advantage of an air bubble in a curved glass tube is that it is virtually dead still, which a plumb bob never is.
Level
OTHER NAMES: Spirit level, plumb rule
SIZE: 3 to 78in.
MATERIAL: Aluminum, hardwood, plastic
USE: To determine the accurate level of a surface
The important part of any level is the vial. This is a curved or barreled glass or plastic tube containing a clear liquid which may be alcohol, oil or chloroform. There is a bubble of air in the liquid which floats to the highest point of the curve, where two lines are marked on the vial. When the level is "true" the bubble will come to rest between the two marked lines. The vial is protected by a transparent cover and can be replaced if necessary.
Vials are fitted in levels of various kinds. The simplest is a small pocket level, which contains one vial. A "line" level is similar in size, but is fitted with a hook at either end to locate it on a taut cord. This insures that the leveling line is truly horizontal. Standard levels are parallel top and bottom, ranging in length from approximately 9in. up to 78in. The shorter 9in. levels are often tapered at both ends. These are known as "torpedo", "canoe" or "boat-shaped" levels. The longer the level, the more accurate the reading. Longer levels contain several vials for measuring horizontally and vertically. Some are set at 45 for measuring angled surfaces.
Before buying check that the level is true by setting it up on a surface already established as truly horizontal.
Water level
Make a water level to determine the evenness of two points that are separated by distance or obstruction. Fit short lengths of transparent plastic tube at each end of a hose pipe. Fill the pipe with water until it appears in the tubes. The water will automatically level itself.
Chalk Line
OTHER NAME: Chalk box
SIZE: 18 to 100ft
MATERIAL: Cotton, plastic
USE: To snap a marked line
A chalk line is used to mark a straight line on a surface. This may be a plumbed line on the wall for hanging wallpaper vertically, or perhaps a centre line on a ceiling for the application of tiles.
In the best models, the line is contained in a case with colored chalk powder (white, red or blue). As the line is withdrawn from the casing, a felt gasket distributes an even chalk coating. The line has a hook and ring at one end for attaching to a nail or catching between floor boards.
Attach the hook to one end of the surface and extend the chalk line to the other. Pull it taut and flat and "snap" the centre of the line sharply against the surface to transfer the chalk to the surface.
Plumb Bob
OTHER NAME: Plumb line
SIZE: Weight: Hoz to 4Ibs
MATERIAL: Bob: brass, plastic, lead, steel; Line: nylon, silk
USE: To determine a vertical line
The plumb bob is used to make sure that a structure such as a door frame is truly vertical, or that an object is directly under a point on a ceiling. This helps in the siting of a light fixture.
The plumb bob is a pointed weight attached to a length of line which is contained in the bob itself and fastens in a slot in the cap. If the hardened point on the bob end becomes bent it will no longer give a true reading, so must be replaced.
Hold the end of the line at the required point and allow it to settle out of its natural swing. Make sure that it is hanging free, and mark the point below the plumb bob or the edge of the line.
Mason's Line and Pins
OTHER NAME: Bricklayer's line and pins
SIZE: Length: 30 to 60ft.
MATERIAL: Pins: steel; Line: cotton, plastic, nylon, hemp
USE: To make sure that a course of bricks is straight and true
The line is stretched along a wall and secured at either end by flat bladed steel pins.
As you lay the bricks take care that the line is not being pushed out of true.
Small flat metal pins known as trigs are pushed into the mortar joints to support the middle of a long line and prevent it sagging out of true.
Fix one pin around the corner of a wall, locating the fiat section in the nearest vertical joint. Stretch the line and fix it to iha other pin.
Line Block
SIZE: Approximately 4in.
MATERIAL: Block: wood, plastic; Line: cotton, plastic, hemp, nylon
USE: To make sure that a course of bricks is straight and true
This is the same device as the line and pins but uses plastic or wooden L-shaped blocks in place of the pins. The line passes through a slot in the block and is tied off at each end. As the line is pulled tight the blocks hold their position by friction on the bricks.
Fixing the block
Attach the block to one corner of the wall. Pull the line taut and attach the other block at the next corner.
