The Martins are veteran travelers in England and on the Continent and, after a half-dozen informational guidebooks, they're no longer bothering with such basics as restaurants, hotel reservations and exchange rates. In fact much of this entertaining but certainly inconsequential book is devoted to antiquated trivia -- did you know that the Forge in the Parish of St. Danes pays its annual rent to the Crown by presenting 61 nails and six horseshoes to the Royal Remembrancer? Oddments and historical eccentricities are the Martins' specialty and England, France, Italy, West Germany, Switzerland and the Netherlands all have their share. The chateaux of Touraine, now peaceful and idyllic, are haunted by 16th century royal assassinations; in Verona, Juliet's house with that famous balcony is on the Via Capello; the citizens of Amsterdam have a pet name for their city, ""Mokum"" -- though none of them seems to know what it means. The Martins include a few words on national character -- the Italians live in a perpetual din; the French are obsessed with la cuisine, the Dutch are fond of hurdy-gurdy music and herring. Miscellanea.