Shows how to use a transit to locate a building correctly on the lot, plan proper grades with minimum excavation, find Building Layout Author, W.P. Jackson. Building Layout,WP Jackson. Shows how to use a transit, to locate a building correctly on the lot, plan grades with minimum excavation, find utility lines. : Building Layout () by W. P. Jackson and a great selection of similar New, Used and Collectible Books available now at great.
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Sensitivity in seconds ” per 2mm division of level tube Radius of curvature in feet 14′ ” 1′-7″ 8′ ” 2′” ” 13′-6″ 90″ 15′ 75″ 18′ 60″ 23′ 45″ 30′ 30″ 45′ 20″ 68′ Radii of Level Tubes of Different Sensitivities Table By sighting horizontally through a right angle prism, you see the point over which the transit is centered.
Leveling vials are available in various degrees of sensitivity. An engineer normally measures angles from the north-south meridian in surveying, so the engineer’s transit is equipped with a compass.
Crosshairs in the telescope permit the object sighted to be centered in the field of view. When the bubble moves even slightly on any transit, you will see a movement in the line of sight as indicated by the crosshairs in the field of vision. Instruments designed for still greater precision have a vernier that further subdivides each minute into seconds.
The more precise instruments whose vernier or optical micrometer scales read in the seconds would have level tubes in the 20 to 45 seconds sensitivity range.
Building Layout – Surveying Guides – Books and Software – Craftsman Book Company
There is no substitute for accurate layout of foundations, walls and floors. An instrument whose vernier only reads to 15 minutes would probably have a level tube with a sensitivity of 8 to 14 minutes or “” per 2 mm.
Figure shows two theodolites, each with a micrometer scale. See Figures and Plumbers need them to lay out sewer lines.
Instead it will be centered over another point, a, resulting in an erroneous reading. Sensitivity in seconds ” per 2mm division of level tube.
Table shows the radii of level tubes of different sensitivities. But if it is not set up and leveled properly, accurate work is impossible regardless of how accurate the instrument is. This book is the result of his interest in improving professional standards among builders. The wind has no effect on the optical plummet; it can be a factor with the plumb bob.
If the center of the tripod head is not approximately over the point, centering the transit with the plumb bob or optical plummet isn’t possible. The w.pjackson that comes with each w.p.jackosn gives step by step instructions for setting up and leveling the instrument. Figure shows a transit with a 20 second vernier reading. The instrument is set up over A, centered over the tack and properly leveled. The accuracy in all readings and surveying tasks requires a level instrument at all times.
An instrument with a 5 minute vernier reading would probably have a level tube whose sensitivity would be from 90 to seconds per 2 mm, and an instrument with a 1 minute vernier reading would probably be in the 60 to 75 seconds per 2 mm sensitivity range. The builder’s or contractor’s transit, or transit-level, does not normally include a compass because buildings are laid out from an existing fixed point at or near the building site, such as the lot corner stake or monument.
Line a-b is parallel to the line of collimation of the telescope and is perpendicular to b-cwhich is the ray of light from the right angle prism at b to the target at c. The list can include farmers, landscapers and many others. Level Tube Sensitivity The more sensitive the level tube, the greater the precision that may be obtained.
Since you use a transit for its accuracy, there is no substitute for an accurate instrument regardless of the size of the job. Hundreds of valuable suggestions are included: Theodolites are used where precision work is essential.
They will not be covered here, but you should know the reason for some of the operations and how they can affect the accuracy of your work. The theodolite has an optical plummet, and the sensitivity of the level tube is usually 45″, or better.
Telescopes come in one of two types: Set the tripod on firm ground and make sure the tripod points are stuck well into the ground. There are three main parts to any transit — the telescopethe leveling vialand the circle. It will be centered on different points such as a when the telescope is revolved.
You may not need that degree of precision now, but you probably will need it later when your skills increase and you take on other types of jobs. For example, a 20x telescope makes a distant object appear 20 times closer than if viewed with the naked eye.