Baseline building, Lough Foyle
Date
1830
Creator
Unknown, Artist
Object type
Archive reference number
Material
Dimensions
height (drawing): 160mm
width (drawing): 303mm
width (drawing): 303mm
Subject
Content object
Description
Elevation of the proposed building intended to protect the baseline used in triangulation measurements for the Ordnance Survey of Ireland, supervised by Thomas Colby.
An accompanying letter by Thomas Colby, Ordnance Map Office, Tower of London, to Davies Gilbert explains the purpose of the construction: ‘The places for the points are marked by blocks of sandstone 4 feet in diameter, having foundations 8 feet in diameter; and the points themselves are the ends of pieces of platina wire about six inches in length, which are let perpendicularly into the blocks, and secured with lead and roman cement. To secure the blocks from every external force, and the points of the wire from injury are the immediate objects of the proposed buildings…’
Inscribed below right: ‘Scale 4ft to an Inch’.
Thomas Frederick Colby (1784-1852) surveyor and army officer, was elected a Fellow of the Royal Society in 1820.
An accompanying letter by Thomas Colby, Ordnance Map Office, Tower of London, to Davies Gilbert explains the purpose of the construction: ‘The places for the points are marked by blocks of sandstone 4 feet in diameter, having foundations 8 feet in diameter; and the points themselves are the ends of pieces of platina wire about six inches in length, which are let perpendicularly into the blocks, and secured with lead and roman cement. To secure the blocks from every external force, and the points of the wire from injury are the immediate objects of the proposed buildings…’
Inscribed below right: ‘Scale 4ft to an Inch’.
Thomas Frederick Colby (1784-1852) surveyor and army officer, was elected a Fellow of the Royal Society in 1820.
Associated place