What is Dumpy Level?
What is a Dumpy Level?
A dumpy level, also known as an automatic level or builder’s level, is a leveling instrument used to determine the points in the same horizontal plane. It is used to identify the elevations of different points and measure the distance between points of the same elevation. Invented by William Gravatt in 1832, a dumpy level has a telescope that is fixed to its supports and cannot be rotated in the vertical axis.
Uses of a Dumpy Level
Dumpy levels are commonly used in construction and surveying projects as they are highly accurate in determining points in the same horizontal plane. They are also used in civil engineering, land surveying, and mining. With the help of a dumpy level, one can measure the difference in elevation between two points, calculate the distance between two points of the same elevation, and set up a survey line.
Benefits of a Dumpy Level
The primary benefit of a dumpy level is its accuracy and precision. As it can measure the difference in elevation between two points, it is very efficient in locating points in the same horizontal plane. Another advantage of a dumpy level is that it can be used in various terrains,
Components of Dumpy Level
Telescope:
The telescope is an essential component of the dumpy level. It is used to identify and adjust the position of the instrument correctly. It is a long tube, often made of metal, with a lens at the top and bottom.
Bubble Tubes:
Bubble tubes are used to determine the level of the instrument. They are made up of two transparent plastic tubes which are filled with a liquid. The tubes are angled so that when the instrument is level, the liquid forms a bubble in the middle of the tubes.
Compass:
The compass is used to orient the instrument correctly. It is designed to detect and indicate the direction of the magnetic field.
Vertical Spindle:
The vertical spindle is used to measure the angles of the instrument. It is a device with a rotating disc and a graduated scale. The disc can be rotated to measure angles and the scale can be used to read the angle measurements.
Tribrach Screws:
Tribrach screws are used to attach the instrument to the tripod. They are small screws that are used to secure the instrument to the tripod.
Foot Screws:
Foot screws are used to level the instrument. They are small screws that are used to adjust the instrument’s height and level.
Leveling Head:
The leveling head is used to adjust the instrument’s position. It is a device with a rotating disc and a graduated scale. The disc can be rotated to adjust the instrument’s position and the scale can be used to read the angle measurements.
Tripod:
The tripod is used to support the instrument and keep it steady. It is a three-legged stand, usually made of metal, with adjustable legs. The legs can be adjusted to ensure the instrument is level and stable.
Telescope
WHAT IS A TELESCOPE?
A telescope is a device used to observe distant objects by collecting electromagnetic radiation. Telescopes are typically mounted on a vertical spindle of a dumpy level in order to allow for rotation along the vertical axis.
HOW DOES A TELESCOPE WORK?
A telescope works by collecting and magnifying light from distant objects in order to make them appear larger and brighter. The telescope is able to do this by using a combination of lenses and mirrors, which are arranged in a specific way to capture and focus the light from the distant object.
WHAT IS A DUMPY LEVEL?
A dumpy level is a surveying instrument which is used to measure height differences. It consists of a vertical spindle which can be rotated along its axis, allowing the telescope to be pointed in different directions. This is important for accurately observing distant objects.
Parts of Telescope in Dumpy Level
Eye Piece:
What is an Eye Piece and How Does it Work?
The eye piece is an important part of a telescope and is used by the observer’s eye to view distant objects. It contains a magnifying glass which magnifies the observing image and also has cross hairs of a diaphragm. This allows for accurate readings to be obtained. An erecting eye piece is also used to view a normal image which is inverted by the objective lens.
Objective Lens:
What is an Objective Lens and How Does it Work?
The objective lens is located at the other end of the telescope and is made up of two parts. The front part consists of a convex type lens and the back part consists of a concave lens. This means that the image obtained from the objective lens is always inverted.
Diaphragm:
What is a Diaphragm and How Does it Work?
A diaphragm is located in front of the eye piece and contains cross hairs made of dark metal which are arranged in perfect perpendicular positions. These cross hairs are used by the eye piece to bisect the objective through the objective lens.
Focusing Screw:
What is a Focusing Screw and How Does it Work?
The focusing screw is used to adjust the focus of the telescope. It is a mechanism that allows the telescope to be adjusted to the correct distance and angle for the observer to view the subject.
Ray Shade:
What is a Ray Shade and How Does it Work?
The ray shade is a circular disc that is placed over the objective lens of the telescope. It helps to reduce the amount of light entering the telescope, which makes it easier to view the subject. It also helps to protect the objective lens from dirt, dust and other particles.
Focusing Screw:
What is a Focusing Screw?
A focusing screw is a device that is used to adjust the focus of cross hairs and the image clarity. It is used to control the magnification of the eyepiece. This enables the user to see the image in much greater detail.
How Does a Focusing Screw Work?
A focusing screw works by adjusting the distance between the eyepiece and the objective lens. This adjustment changes the focal length of the device, allowing the user to bring the image into focus. The focusing screw can be adjusted by turning it with a screwdriver or other tool. The amount of adjustment depends on the device and the type of eyepiece being used.
Ray Shade:
What is a Ray Shade?
A ray shade is a device that is used to prevent light from entering the objective lens of a device. This helps to keep the line of sight clear, allowing the user to view the image with better clarity and detail. The ray shade works by blocking out sunlight or other bright light sources that could cause glare or distort the image.
How Does a Ray Shade Work?
A ray shade works by blocking out any light that enters the objective lens of the device.
Bubble tubes
Overview of Bubble Tubes
Bubble tubes are a critical component of a dumpy level and are used to check the level of the instrument. Generally, two bubble tubes are provided on the top of the telescope and are arranged perpendicular to each other.
Cross and Longitudinal Bubble Tube
The two bubble tubes used in a dumpy level are the cross bubble tube and the longitudinal bubble tube. The instrument is said to be in perfect position when the bubbles of the tubes are centered in the middle of the tube.
Ensuring Perfect Position of Instrument
Checking the level of the instrument is an essential part of the dumpy level. To ensure that the instrument is in the perfect position, both the cross and longitudinal bubble tubes should be at the center of the tube.
Compass
Using a Compass to Determine Magnetic Bearing
Compasses are a useful tool for measuring the direction of a line in relation to magnetic north. A circular compass is typically provided with a dumpy level, and is located underneath the telescope. The compass contains a pointer, and readings are marked inside the compass. To get an accurate reading, the pointer needs to be set to zero when it is facing the north line. This will ensure that the magnetic bearings are accurately measured.
Vertical spindle
- Introduction to Vertical Spindle
The vertical spindle is a central component of a telescope that allows it to be rotated horizontally in relation to the spindle’s vertical orientation. This spindle is connected to a tripod stand, enabling the telescope to be used in a variety of observational settings.
- Benefits of Vertical Spindle
The vertical spindle provides a steady, secure connection between the telescope and the tripod stand, allowing for precise and reliable movements of the telescope. This makes it easier to capture clear images of distant objects. Additionally, the vertical spindle allows for a wide range of motion, providing the user with a greater range of view.
- Usage of Vertical Spindle
The vertical spindle is an essential component for any telescope, allowing for the device to be used in various observational settings. Telescopes equipped with a vertical spindle offer the user greater control over their observational experience, allowing them to capture clearer images and take in a wider range of views.
Tribrach
What is a Tribrach Plate?
A tribrach plate is a type of leveling plate that is connected to a trivet or leveling head. It is used to adjust the horizontal level of an instrument by adjusting the leveling screws or foot screws that attach the tribrach plate to the trivet.
What are the Benefits of Using a Tribrach Plate?
Using a tribrach plate provides a precise and consistent level for surveying and other instruments. The tribrach plate allows for precise and easy adjustment of instrument levels, providing accurate readings and data.
How Does a Tribrach Plate Work?
The tribrach plate is mounted parallel to the leveling head or trivet, and the leveling screws or foot screws can be adjusted to achieve the desired horizontal level. By adjusting the tribrach plate, it is possible to achieve the desired level of precision and accuracy.
Foot screws
Regulating the Tribrach Position
Foot screws are used to regulate the tribrach position of a survey instrument, which is important for the instrument to be leveled. This can be done by observing the bubble tube, where the position of the tribrach is said to be correct when the bubble is at the center.
Adjusting the Tribrach with Foot Screws
The tribrach plates can be adjusted with the help of foot screws. By raising or lowering the tribrach plates, the survey instrument can be leveled and the bubble in the bubble tube can be centered.
Leveling head
What is a Leveling Head?
A leveling head, also known as a trivet, is an essential tool for leveling surfaces. It consists of two parallel triangular plates with foot screws supported in the three grooves at the three corners.
How Can a Leveling Head Be Used?
A leveling head can be used to level off surfaces by adjusting the foot screws in the grooves until the desired level is achieved. It is a useful tool for engineering and construction applications, where a level surface is often required.
Tripod
What is a Tripod?
A tripod is an instrument support that is composed of three adjustable legs used to level the device that is placed on top. The legs are of an equal length and can be either hollow or solid. Steel shoes are attached to the bottom of each leg to ensure the tripod remains in a stationary position.
How Does a Tripod Work?
The tripod is used to support a levelling device. The three adjustable legs can be adjusted to the desired position. Steel shoes at the bottom of each leg ensure that the tripod remains firmly in place. The legs are all equal in height, and can be either hollow or solid.
What are the Benefits of Using a Tripod?
The tripod is an invaluable tool for levelling devices. It ensures that the device remains in a fixed position, and its adjustable legs allow for a wide range of angles and heights. It is also constructed from strong materials, such as steel, for long-term durability.
Procedure of Dumpy Level Surveying
Setting up the Instrument
The first step in dumpy level surveying is setting up the instrument. This involves placing the dumpy level on a tripod stand and ensuring that the instrument is level and stable. The focusing mechanism is then adjusted so that the level is in focus.
Leveling Up
The next step is to level up the instrument. This is done by adjusting the three leveling screws on the tripod stand to ensure that the instrument is in the correct position. This step is important as it ensures that the readings taken are accurate.
Focusing
Once the instrument is in the correct position, the focusing mechanism is adjusted to ensure that the level is in focus. This is done by adjusting the eyepiece and focusing knobs to adjust the focus of the instrument’s lens. This step is important to ensure that the readings taken are accurate.
Setting up of Dumpy Level
Positioning the Instrument
To position the instrument, first spread the legs of the tripod stand and adjust it to a convenient height. Next, secure the two legs on the ground at a point and use the third leg to center the bubble in the bubble tubes. Finally, use clamp screws to fix the instrument to the tripod stand.
Leveling up
Step 1: Arranging Telescope Parallel to Leveling Screws
The leveling up of an instrument, such as a telescope, is usually done by using foot screws or leveling screws. To begin the process, the telescope should be arranged parallel to any two leveling screws.
Step 2: Centering the Bubble in the Tube
Once the telescope is arranged, the bubble in the tube should be centered by turning the two screws either inwards or outwards. When the bubble is at the center, the telescope can then be turned 90 degrees and the third screw should be turned until the bubble once again comes to the center.
Step 3: Repeating the Process
To ensure that the bubble consistently stays at the center in any position of the telescope, the above process should be repeated.
Focusing
Focusing the Telescope
Focusing the telescope involves adjusting the eye piece and focusing screw to obtain a clear vision of the cross hairs of the diaphragm. To eliminate any parallax error, a white paper should be used to help achieve a sharp vision. Once the cross hairs are bisecting the objective or staff with a clear vision, focusing is complete.
Taking Levels
Once the telescope has been focused, it is time to take levels of the required points. The telescope is rotated to line up with the objective or staff and bisect it. The levels are noted at different points, which are determined by a known bench mark in the area. The details of the levels should be tabulated for future reference.
| Position observed | Level reading | HCR (higher cross hair reading) | LCR (lower cross hair reading) | (HCR-LCR) x 100 | Distance of point from instrument | Remarks / Error |
| 1 | ||||||
| 2 | ||||||
| 3 |
Benefits of Dumpy Level Surveying
Ease of Use of Dumpy Level
Dumpy level is an easy to use instrument which can be used on any type of ground to make necessary adjustments.
High Accuracy of Level Readings
The level readings obtained from dumpy level are very accurate due to its high optical power.
Affordability of Dumpy Level
The price of dumpy level is relatively cheaper when compared to other surveying instruments, making it a cost-effective option.
Drawbacks of Dumpy Level Surveying
Limitations of Dumpy Level
Dumpy level is a type of tool used to measure horizontal angles. Despite its convenience, it has certain limitations that should be taken into consideration.
Accuracy of Dumpy Level Measurements
The accuracy of dumpy level measurements is not as precise as other angle measuring tools. This can be problematic for applications that require high levels of accuracy.