Sentence:  Lineal conſanguinity is that which ſubſists between perſons, of whom one is deſcended in a direct line from the other: as between John Stiles (the "propoſitus" in the table of conſanguinity) and his father, <WSD>grandfather</WSD>, and great-<WSD>grandfather</WSD>, and ſo upwards in the direct aſcending line; or between John Stiles and his ſon, grandſon, great-grandſon, and ſo downwards in the direct deſcending line. 
Meaning of the word marked with <WSD> tags:  A father of someone's parent. (from 15th c.)