Ordnance Survey's Levelling of Great Britain

[2GL Abstract] [2GL Transcription]

References and Links to Other Websites

2GL Abstract by Colonel Sir Charles Close 1921

Listing of the Intermediate points used in Primary Lines in England and Wales in 2GL Abstract

Companion Volume provides background on Levelling

Map of 1GL (as a plate)

Files and Images held at The National Archive, Kew.

See Index of all Levelling Files (as at 22/9/04)

See Index of 2GL Abstracts includes Primary in Scotland, Secondary Lines and Tertiary Areas

See copies of a selection of Glass Lantern Slides

Ordnance Survey Maps - a descriptive manual, JB Harley 1975

Network of the third geodetic levelling [Fig 4] (p10) [similar to Map of 3GL]

Also some background on Levelling and construction of FBM's etc

Roger Hellyer, The 'Ten-Mile' maps of the Ordnance Surveys (CCS 1992)

Refers to maps of Triangulation and Levelling, see Glass Lantern Slides

National Tidal & Sea Level Facility Website

Map of 3GL (incorrectly labelled as 'first half of the 1900s' it appears to show 3GL - 1950's)

Details On Tide Guages

Abstracts of the principal lines of spirit levelling in England and Wales / by Henry James. (1861)

(Abstract of the First Geodetic Levelling)

Index

list of intermediate points being scanned as you read this!

Other Websites Used in Building this website

• Trigonomy Yahoo Group - active discussion on many aspects of levelling
• OSBM MSN group - members have uploaded locations and photos of many FB's
• Fayers - lists locations of most of the FBM's
• T:UK - many members have visited and logged reports of FBM's
• National GPS Network - details of Passive stations and FBM's - also some background on levelling
• Numerous other sites used to build the timeline (listed at the bottom of the page)