"When the ancestor, by any gift or conveyance, tak- eth an estate of freehold, and in the same gift or conveyance an estate is limited, either mediately or immediately, to his heirs in fee or in tail, the 'heirs' are words of limitation of the estate, and not words of purchase." 1 Coke, 104. Intimately connected with the quantity of estate which a tenant may hold iu realty is the antique feudal doctrine generally known as the "Rule in Shelley's Case," which is reported by Lord Coke in 1 Coke, 936, (23 Eliz. in C. B.) This rule was not first laid down or established iu that case, but was then simply admitted in argument as a well- fouuded and settled rule of law, and has always since been quoted as the "Rule in Shel- ley's Case." Wharton.