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Surveyor's view of the levelling rod with the crosshair. This indicates a reading of 1.422 m, interpolated between the 1.420 m and 1.430 m marks. Rods come in two classes: Self-reading rods (sometimes called speaking rods). Target rods. Self-reading rods are rods that are read by the person viewing the rod through the telescope of the instrument.
The rod is used in levelling procedures to determine elevations and is read using a level. A Philadelphia rod consists of two sliding sections graduated in hundredths of a foot. On the front of the rod the graduation increasing from zero at the bottom. On the back of the rod the graduation decrease from 13.09 ft at the bottom to 7 ft.
The top mark is at 1,500 mm and the lower is at 1,345 mm; the distance between those two marks is 155 mm, yielding a distance to the rod of 15.5 m. Optical levelling, also known as spirit levelling and differential levelling, employs an optical level, which consists of a precision telescope with crosshairs and stadia marks.
The Y level or wye level is the oldest and bulkiest of the older style optical instruments. A low-powered telescope is placed in a pair of clamp mounts, and the instrument then leveled using a spirit level, which is mounted parallel to the main telescope. The term dumpy level (also builder's level) endures despite the evolution in design. They ...
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Target is lowering prices on more than 2,000 items across an array of categories in a bid to offer more discounts to cash-strapped customers as the holiday season approaches.
An Ordnance Survey cut mark in the UK Occasionally a non-vertical face, and a slightly different mark, was used. The term benchmark, bench mark, or survey benchmark originates from the chiseled horizontal marks that surveyors made in stone structures, into which an angle iron could be placed to form a "bench" for a leveling rod, thus ensuring that a leveling rod could be accurately ...
On Monday, Target slashed prices on more than 1,500 items, ranging from laundry detergent to cat food to sunscreen, with thousands more price cuts expected over the summer. For example, the price ...