 Published in the same issue of the New England Historical and Genealogical Register with the Arnold family record was another article giving a lineage for William Arnold going back 16 generations . In 1870 the genealogist Horatio G. Somerby compiled this pedigree of the Arnold family for a client in New York based on his research in England . In this pedigree , William Arnold was shown to be a son of a Thomas Arnold and to descend from a 12th @-@ century King of <unk> ( in modern day Wales ) whose name was <unk> . Mr. Somerby 's manuscript was " compiled from Herald 's Visitations , Inquisitions Post Mortem , Subsidy rolls , Wills , Parish registers , and other original documents . " A few years after this pedigree was published , John O. Austin incorporated some of it into his Genealogical Dictionary of Rhode Island . 
