Map Collections at UCD and on the Web: Scales, Symbols, Coordinates & Indexes
Scales & Series
The following are examples of maps of differing scale. Use this composite to compare scales.
Mapping at 1:1000 (approx. 5" to 1 mile), see this sample map, began at the end of the 1960s for Dublin, Cork, Galway, Limerick and Waterford cities. This has extended over the years and this scale is now available for urban areas with a population in excess of 1,500 (approx). Revisions are now running at about every 1-2 years.
The 1:2500 scale comprises maps from both the older 25" series and the newer 1:2500 series. The old 25" series covers all areas of the country except for remote rural regions. For more information about the old 25" series see Trinity Map Library's description. The newer 1:2500 series covers suburban and peri-urban areas and is revised approximately every 3 years.
1:5000 (approx. 12" to 1 mile): mapping at this scale covers rural areas and is updated approximately every 5 years.
1:10,560/(6" to 1 mile) : maps at this scale are available for the whole of Ireland but have not been updated since the 1930s. For more information about this series see Trinity Map Library's guide on 6" maps.
1:50,000 Discovery Series. Richview Library has complete sets of these series.
How to find the date of an OSi six inch or 25 inch historic map
Ordnance Survey Ireland (OSi) National Townland and Historical Map Viewer allows you view the historic 25 inch and 6 inch mapping series. Instructions are provided in the PDF below and the contents are:
Finding townland names and their boundaries pages 1-5
Finding sheet map numbers pages 6-8
Finding dates for the 6inch & 25inch historic maps pages 9-10
Marking and sharing locations of sites pages 11-13
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Finding Townlands and Historic OSi Map DatesThese instructions help you identify and locate townland names in Ireland using the OSi website. You can also find historic map sheets, locate them and find their survey dates.
List of Map Scales
Gives conversion of scales from ratio to standard measurements.
See both documents below for scales and their equivalents.
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List of Map ScalesGives scales in ratio, inches and feet and metres and kilometres
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Common Map Scales & Their EquivalentsThis is an alternative document which gives map scales and their equivalents in inches, centimetres, miles and kilometrres.
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Scale CalculatorThis website MapTools - Tools for Navigation, provides some free resources and information on coordinate systems, scales, navigation and calculators.
OSi Characteristic Sheet
The OSI characteristic sheet provides a guide to symbols used on the 25inch and 6inch maps.
Indexes
Visual index maps: these exist for most of the series of maps in stock in Richview Library and provide a visual way of relating the area you require to an Ordnance Survey Ireland (OSI) map number.
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Indexes to the 1/2500 and 6-inch scale maps and small specimens of different maps published byPublication Date: [1908]Visible indexes for all published 25 inch and 6 inch maps for the 32 counties on the island of Ireland.
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Maps and Plans and Other Publications of the Ordnance Survey of Ireland to May 1894Includes indexes for various series and also lists Town Maps, Dublin Parish Maps and One Inch Maps, etc
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Index to 1-1000 Maps for Dublin CityThis 1968 Ordnance Survey map index shows the 1:1000 sheet numbers for the area extending from Dublin city centre out to Finglas, Blanchardstown, Baldoyle, Howth, Foxrock, Killiney, Sandyford, Oldbawn, Edmondstown, Tallaght, Castleknock and Palmerston.
Tools for Finding and Converting Coordinates
General information on geographical co-ordinates and map projections are provided here on the ICA Commission on Map Projections website
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CoordtransCoordTrans converts geographic coordinates between different coordinate systems.
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GeoNamesHelps you find the latitude and longitude of any location or placename in the world. Enter the required location into the search box, click search and the latitude and longitude details will be displayed.
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Find latitude and longitude using Google MapsView the single image to see how to get the longitude and latitude coordinates for your site or address
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The World Converter ToolView the single image for an example of how to use TWCC. "The World Coordinate Converter", is an Open Source tool to convert geodetic coordinates in a wide range of reference systems.
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Ordnance Survey Ireland Coordinate ConverterIn this example the numbers 681693 and 637876 were typed into the ITM Easting and Northing boxes. Click on Convert. The coordinates will pop up in the other standard co-ordinate systems, i.e. Lat / Long, UTM and Irish Grid.
Link to OSi co-ordinate converter: https://gnss.osi.ie/new-converter/
The OSI website also provides a free downloadable co-ordinate converter at: https://www.osi.ie/services/geodetic-services/download-co-ordinate-converter/
OSi Presentation on Scales
Click on the Powerpoint below for an OSi presentation on large and small scale mapping.
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Scales and MapsThis is a Powerpoint presentation from OSi which explains large scale and small scale mapping
Enlarging and Reducing Sheet Maps
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original scale: |
% to select on copier: |
map scale now equals: |
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1:1000 |
200% |
1:500 |
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1:500 |
200% |
1:250 |
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1:500 |
250% |
1:200 |
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1:250 |
125% |
1:200 |
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1:1000 |
50% |
1:2000 |
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1:2000 |
80% |
1:2500 |
US Geological Survey Scales Fact Sheet
This Fact Sheet from the US Geological Survey describes and explains how scales work in maps.
Creative Commons license
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