A lock level is a device people use in surveying to improve the accuracy and reliability of measurements. Surveying equipment can include a lock level to allow people to fix the surveying level in place with the use of a locking nut while collecting data. Surveyors can use multiple locking nuts to fix levels at different angles, collecting a variety of useful data about the topography at a site. It is important to avoid confusing this term with a Locke level, a surveying tool developed by American inventor John Locke.
In the course of performing a survey, people take a wide variety of measurements to gather as much data as possible about an area, ranging from a job site to a mountain top. The surveyor uses sighting and measurement tools to determine things like the grade and inclination of the topography, and can use a lock level for leveling measuring tools to take multi-part measurements. The equipment typically mounts on a staff or tripod and may be used by a single person or a pair of surveyors taking coordinating measurements.
When a piece of equipment includes a lock level, it will specify this in the technical data along with other information about the features on the equipment and the most suitable uses. The technical documentation will usually include a manual providing information about how to use and care for the instrument so people can make sure their surveying is as accurate as possible.
The lock level improves the precision of surveying by stabilizing the instrument when the surveyor finishes taking a measurement. Lock nuts have very precise machining so they will operate smoothly and easily, eliminating problems like disturbing the measurement while trying to crank them tight. It is important to make sure they are regularly cleaned and oiled, as detritus in the mechanism can disturb the accuracy. Surveyors may also calibrate using other tools to make sure the measurements taken by a piece of equipment are accurate.
The Locke level is a handheld sighting tube people can use to collect information about the environment around them. It is also possible to mount it on a staff for some kinds of measurements. Using a sighting tube provides opportunities for looking into the distance and taking accurate measurements. It is possible to make a simple Locke level at home, and this is sometimes an exercise in science classes when students learn about surveying.