There's a phrase in Latin that goes errare humanum est which roughly translates as everyone makes mistakes. This is true of so many things and maps are no exception. However much we try to make today's maps as authentic, up to date and accurate as we can, the occasional mistake slips in; it's more a case of when rather than if.

But if you find a mistake in a map, is it really a mistake or it is a deliberate error, placed there as a copyright trap to provide evidence of the origin of a copied map? This is a vague area at best. Some map makers are up front about this.

Take the iconic Geographers' A-Z maps in the UK. Just off of Canynge Square in Bristol there's a small side street called Lye Close. Or is there? The map says there is but if you go to that location you'll just find an unbroken row of houses and Lye Close is nowhere to be found.

The Geographers' company has freely admitted that its maps contain trap streets and Lye Close looks to be one of them. The company mentioned about 100 trap streets in London alone in the BBC program Map Man, broadcast in October of 2005.

But other mapping mistakes are somewhat more mysterious.

In 2009 a phantom town called Argleton appeared on Google Maps. Argleton was in the middle of empty fields close to the M58 motorway in Lancashire. But if you go there now, it's nowhere to be seen. Mapping error or copyright trap? No-one has yet confessed to Argleton although you'd be forgiven for verging into conspiracy theory territory as Argleton is an anagram of Not Real G.

Then there's the case of Sandy Island, which apparently lives in the South Pacific, somewhere between Australia and New Caledonia. Go to Google Maps and Nokia Maps and there's definitely an island shaped blob in the ocean. Yet when scientists from the University of Sydney went to find Sandy Island they found unbroken ocean, over four and a half thousand feet deep.

Mapping error or copyright trap? I suspect the former in this case. There's a significant difference in putting a copyright trap into a map in a rural area or a small side street in a major city and putting an island on a map that just doesn't exist. A land based copyright trap probably won't cause harm, but an ocean based one could, especially given the reliance on marine charts that boats and ships have.

Trap streets and other copyright traps are the mapping equivalent of a Googlewhack. As soon as you know they're there they usually disappear and are replaced by something else that is as yet unpublicised.

Updated

Thanks to Steve Chilton, Elliot Hartley and Tom Hughes it looks like Sandy Island may well have been an error for over 100 years. The Auckland Museum has maps from 1908 which show Sandy Island.

Photo Credits: OpenStreetMap, The Daily Telegraph and The Auckland Museum.