Do you have any old maps of Irish interest? If so, you could be in a seller's market. Mr Fonsie Mealy, an expert in maps and books at Mealy's auctioneers in Castlecomer, Co Kilkenny, says they have several collectors trying to collect "any map ever done on Ireland".

The first thing to look for in a map is rarity and then condition. "A lot of maps were coloured - they're the ones worth the money," says Mr Mealy. But he warns that maps coloured subsequently by printers are worth far less.

Moreover, reprints of maps - even old ones - do not command the same price as originals. For instance, Sir William Petty's county map of Ireland from about 1680 should fetch £600 to £800 in good condition. But the second edition, issued by Grierson in the 1730s, is only worth about £300 to £400.

Mr Mealy points out, however, that it isn't always evident whether a map is original or a reprint. You can sometimes only tell by examining the differing watermarks on the paper.

Mr David Park, head of the books and manuscripts department at Bonhams in London, enthuses about a collection of maps and books of Irish interest to go under the hammer at its auction next Tuesday and Wednesday.

There's a large 1714 map of Ireland (1,016 by 612 millimetres), a "beautiful map in two sheets with attractive insets" showing plans of the Giant's Causeway, Waterford, Cork, Dublin, Limerick and Kinsale harbour. Designed by Herman Moll - "one of the best-known English map makers of the first quarter of the 18th century" - it is a hand-coloured engraved map. The key shows the deployment of troops in Ireland and a small map of northern Europe. It is "quite modestly estimated at £400 to £600", says Mr Park.

"A slightly later but equally impressive map" by John Rocque is also in the sale. A famous map-maker, he also "did a very wellknown and highly valued street plan of Dublin in the same period. And one of London". The Rocque map of the Kingdom of Ireland circa 1760 measures 1,229 by 965 millimetres and is done in a "fairly monumental style". It is engraved on four sheets joined as pairs, handcoloured in outline and its inset has a large decorative cartouche - the fancy bit around the title of the map - and a map of Britain. It is estimated at £300 to £400 sterling.

Other items of Irish interest in the Bonhams sale include: a near complete collection of first editions by Somerville and Ross (estimate: £1,200 to £1,800 sterling); a first edition copy of Poetry and Ireland by W.B. Yeats and Lionel Johnson, 1908 (estimate: £180 to £220 sterling); an autographed letter by Sir John Perceval signed to the Chief Justice of Common Pleas in Ireland, John Keating, concerning the activities of "tory" outlaws in the last days of the reign of Charles II (estimate: £250 to £300 sterling); and a signed Victorian photograph of Oscar Wilde (estimate: £1,500 to £2,000 sterling).

For further information on the Bonhams sale, ring Mr David Park before September 22nd on 00 44 171 393 3986.