Complex sentence: Arthur William Moore analysed the origin of Manx surnames in use at the beginning of the 19th century: of 170 surnames, about 100 (65 percent) are of Celtic origin while about 30 (17.5 percent) were of Norse-Gaelic origin.
Split into simpler sentences: Arthur William Moore analysed the origin of Manx surnames in use at the beginning of the 19th century. Of 170 surnames, about 100 (65 percent) are of Celtic origin, about 30 (17.5 percent) were of Norse-Gaelic origin.