Mobile CAD Surveying Ltd

What is a Dumpy or Automatic Level

Let us look at the history of surveying levels. Since the Dumpy level was invented in early 1700's it has been considered the standard, that was up until around the 1830's when the transit level was invented. Recently the level has changed faster than you can keep up with it, but through all this the Dumpy level has remained a reliable back up just in case the modern levels breakdown.

A dumpy level, builder's auto level, leveling instrument or automatic level is an optical instrument used in surveying and building to transfer, measure, or set horizontal levels.

The level instrument is set up on a tripod and, depending on the type, either roughly or accurately set to a leveled condition using footscrews (levelling screws). The operator looks through the eyepiece of the telescope while an assistant holds a tape measure or graduated staff vertical at the point under measurement. The instrument and staff are used to gather and/or transfer elevations (levels) during site surveys or building construction. Measurement generally starts from a benchmark with known height determined by a previous survey, or an arbitrary point with an assumed height.

The Dumpy level was a simple device that was nothing more then a small telescope with a bubble level attached to it. The newer Dumpy levels have a few more bell and whistles but are still the same basic design. Some of the drawbacks of a Dumpy level are the time it takes to set up and get level, the slightest mistake in setting it up can result in an inaccurate reading, and taking more then one measurement from different directions can be off if not set up perfectly.

A Laser Level And How It Works

A laser level is a fairly recent invention, and has changed the way surveying is being done. With a self leveling laser level you can be assured that your measurement will be as accurate as humanly possible. A laser level is a level that uses a laser light to project a line. Most surveying laser levels us a rotating mirror so that they can project a horizontal plane around in a circle. A laser level is more accurate then a Dumpy level but can break down from time to time.

As its name suggests, a laser level is a leveler that illuminates a horizontal plane using a laser. It was originally developed by an inventor named Steve Orosz. The laser level works by being stationed on a tripod. This projector also has a rotatable head with a mirror, so that the laser beam can also sweep across the vertical axis. It is adjusted through the many visually interpretable level vials and the numerous screws that must be manually adjusted by a human for correction projection. Then, a staff with an operator equipped to it with a moveable sensor, detects the laser beam and makes an audible signal every time the line is in accordance with the beam. The key behind the laser level is the position of the sensor on the graduated staff, as it interprets the elevation differences between various points on a certain terrain.

There is also a tower mounted laser level. This is often used together with the wheel tractor-scraper, which has a sensor attached to it. This is commonly used during land laser leveling process (such as agricultural lands and when building the foundations of skyscrapers) to flatten the land at a certain degree for a functional drainage system.