To write a tilting level
This is a very delicate instrument and consists of a large number of loose and open parts. Sighting is done with an assistant surveyor who holds a graduated staff vertical at the point under measurement.
Should the instrument be moved to another position within sighting distance, it is re-levelled, and a sighting taken of a known level in the previous survey. The level staff is placed with its foot on the point for which the level measurement is required.
The lower plate can be screwed on to the tripod stand.
The Dumpy level is more reliable due to its solid and rigid construction. But it needs centering of the bubble before taking every reading. Hence bubble can be easily centered. It cannot be removed from its support.
Wye or Y level. The advantages of a Wye level are that the same may be tested for the permanent adjustment rapidly and the adjustment can be made indoors.
Tilting level pdf
Originally, the tilting levels were designed for preliminary works only, but now they have become very popular and are being used for ordinary levelling also. The internal prism mechanism of an automatically levelling telescope. For taking the readings in the reversed position of telescope, the screw is slackened and then the telescope is taken out and reversed end for end. Invention[ edit ] In , English civil engineer and inventor William Gravatt , who was commissioned to examine a scheme for the South Eastern Railway's route from London to Dover , became frustrated with the slow and cumbersome operation of the "Y" level during the survey work, and devised the more transportable and easier to use "dumpy" level,   , so called because of its shorter appearance. Reversal of the line of collimation may be established by interchanging the objective and the eyepiece. Another advantage is that the grades or lines with a particular gradient can be laid by means of the micrometer screw. Tilting Level In this, telescope can be tilted through about four degrees with the help of a tilting screw. Tilting Level. Within a certain range of tilt automatic levelling is achieved by an inclination compensating device. This reduces the complete reliance on the levelling accuracy of the instruments's bottom mount, and the "split bubble" display gives additional assurance that the telescope is level whilst taking the sight.
The Dumpy uses the same basic principle of level sighting. To the body of the telescope, two hanged collars of equal diameters are fixed. They can be manual or automatic - the latter being much quicker to set up.
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