Talk:Spirit leveling

Merge request

see Talk:Spirit level — Graibeard 00:36, 11 November 2005 (UTC)

Spirit leveling

Not sure that this is the correct term for this operation. I will have to ask a surveyor here what they call it. These days laser levels are used on building sites, or the old fashioned guys use dumpies, which have a split mirror view finder, not a spirit level. This article may need to be expanded and updated but I don't have the knowledge to do it.SilentC 21:08, 1 February 2006 (UTC)

I have conducted and witnessed much level work and never have I seen a dumpy level anywhere but in a museum. Laser levels have become very common, but they do not remove the need for spirit levelling. Typically, an engineering surveyor will, with the use of a spirit level (though nobody uses that term much in my surveying experience), set a grade mark on a stake, then the contractors themselves will use that grade to calibrate their own laser level. Once the laser level is set up, it provides vertical reference points from which the builders can measure. -oOo-WhiskeyClone-oOo- 19:17, 25 November 2006 (UTC)

"I have conducted and witnessed much level work and never have I seen a dumpy level anywhere but in a museum" - Just because you've never seen one being used, doesn't mean nobody uses them anymore, now does it? SilentC 21:57, 26 November 2006 (UTC)

Are you saying you encounter them frequently during the course of your duties as a surveyor? May I ask what locale you work in? -oOo-WhiskeyClone-oOo- 21:06, 27 November 2006 (UTC)

Does it look like that's what I'm saying? What I said was that "the old fashioned guys use dumpies". And yes, I have seen a handful of the older builders who still use dumpies. They probably belong in museums but that's bedside the point. They are not surveyors, and neither am I, but that doesn't exclude them from performing this operation. So anyway, what's your point? My point is that I've never heard a surveyor or a builder here in Australia referring to this operation as 'spirit levelling'. Even you called it 'level work' as opposed to 'spirit levelling'. Maybe it's considered an archaic term here, that's why I said I'd have to ask a surveyor. I'll get around to it. SilentC 21:23, 27 November 2006 (UTC)

Sorry I forgot to make my point. I realize that benchmark circuits and other tasks may be performed with instruments that don't use a spirit level bubble (such as the obsolete dumpy level), and therefore the term "spirit levelling" is inaccurate, but I have not been able to find a better term for the operations described in the article. I have always described these operations collectively as "level work," as do the surveyors I work with, but that term sounds a little vague for an encyclopedia. Surveying textbooks I have read tend to use the term "spirit leveling," when describing operations such as benchmark circuits and the grading of stakes. The article seems to describe two things: 1) benchmark circuits; and 2) establishing a vertical datum for a large area. I'm starting to think that the benchmark circuit portion should be cleaned up and made into its own article, and the vertical datum portion (and its equations) should be merged into the Physical Geodesy article (to which it currently refers us for details.) -oOo-WhiskeyClone-oOo- 22:00, 27 November 2006 (UTC)

FWIW, I came here to learn about the technique as used on a global basis to determine the geoid. I believe "spirit leveling" is the most popular term used in that context. -anon

what is that comma immediately following the zero in the img of the second equation (Σ delta-local-h-datum * local-g = 0,) [[1]]

-can't recall my id, not logged in :-) 12 Nov 2006

I do not think the comma has any mathematical meaning: it is just a grammar comma. By the way, I was fascinated by the fact that leveling loops do not close exactly. Does this fact have any name (like the leveling loop paradox or some such)? Where can I read more about it? I have been trying to understand the many definitions of geodesy heights for a long while now. (I still do not understand them, but I begin to understand the problem!) Thanks for providing insight. --Mikael R 13:39, 21 February 2007 (UTC)

I removed that comma, I don't think it is necessary to the sentce being clear and putting it in the mathematics seems to confuse people. RJFJR 18:08, 21 July 2007 (UTC)

rewrite this area

I removed the following as part of cleanup. Seems worthwhile, but needs rewriting before put back in article. Guroadrunner 00:35, 26 October 2007 (UTC)

For the greatest precision the distances to the rods should not be too large, typically 30-60 m, and should be approximately equal in order to eliminate systematic errors such as the residual misalignment between telescope axis and tube level axis.

For measuring height differences over larger distances, multiple point intervals are chained together, and to eliminate systematic errors the reading sequence is "randomized": fb-bf-fb-bf... where fb stands for "forward-backward". In this way, leveling lines are measured that can be interconnected to form a leveling network. The closure of the loops of such a network provide a way to check the correctness of the measurements.

To establish a height system for a country or area for use in construction and infrastructural work like civil engineering, a leveling network covering the country to sufficient density is designed and measured. One or more of the nodes of this network should be coastal tide gauge stations. In this way, it becomes possible to obtain the heights of all the points in the network in a system, or height datum, the zero point of which is given by mean sea level at a tide gauge or ensemble of tide gauges. Height datums thus established will differ slightly between different countries, as the sea surface is not a perfect level surface.