the grandfather and grandmother) one half of John's anceſtors will not be the anceſtors of his uncle: his patruus, or father's brother, derives not his deſcent from John's maternal anceſtors; nor his avunculus, or mother's brother, from thoſe in the paternal line. Here then the ſupply of proof is deficient, and by no means amounts to a certainty: and, the higher the common ſtock is removed, the more will even the probability decreaſe. But it muſt be obſerved, that (upon the ſame principles of calculation) the half blood have always a much leſs chance to be deſcended from an unknown indefinite anceſtor of the deceaſed, than the whole blood in the ſame degree. As, in the firſt degree, the whole brother of John Stiles is ſure to be deſcended from that unknown anceſtor; his half brother has only an even chance, for half John's anceſtors are not his. So, in the ſecond degree, John's uncle of the whole blood has an even chance; but the chances are three to one againſt his uncle of the half blood, for three fourths of John's anceſtors are not his. In like manner, in the third degree, the chances are only three to one againſt John's great uncle of the whole blood, but they are ſeven to one againſt his great uncle of the half blood, for ſeven eighths of John's anceſtors have no connexion in blood with him. Therefore the much leſs probability of the half blood's deſcent from the firſt purchaſor, compared with that of the whole blood, in the ſeveral degrees, has occaſioned a general excluſion of the half blood in all.
But, while I thus illuſtrate the reaſon of excluding the half blood in general, I muſt be impartial enough to own, that, in ſome inſtances, the practice is carried farther than the principle upon which it goes will warrant. Particularly, when a man has two ſons by different venters, and the eſtate on his death deſcends from him to the eldeſt, who enters, and dies without iſſue: now the younger ſon cannot inherit this eſtate, becauſe he is not of the whole blood to the laſt proprietor. This, it muſt be owned, carries a hardſhip with it, even upon feodal principles: for the rule was introduced only to ſupply the proof of a deſcent from the firſt purchaſor; but here, as this eſtate notoriouſly deſcended from
