years old is called "an ancient document," and is said to "prove itself"--_i. e._ to require no proof of its execution, provided it shall have been produced from a custody which may be reasonably and naturally explained, even though not the strictly proper legal custody.--See the late case of Doe _d._ Neale _v._ Sampler, 8 _Adolphus and Ellis' Rep._ 151; and Doe _d._ Wildgoose _v._ Pearce, 2 _Moody and Robinson_, 240. As to the point made by the Attorney-General, at the trial, that where the right is once vested--_i. e._ the instant after the execution of the deed--_such execution_ creating a title to the land in question--that right and title cannot be affected by any subsequent alteration of the deed;--it has been affirmed to be good law in a recent solemn decision of the Court of Exchequer, and confirmed in a Court of Error.--_See Davidson_ v. _Cooper_, 11 Meeson _v._ Welsley, 799-800. "The moment after the execution of the deed, it has become valueless," said Lord Abinger, "except as affording _evidence_ of the fact that it had been executed." In this case, in which the author was engaged, (in 1843,) the whole doctrine of erasures was thoroughly canvassed; and it was decided, on error, that when an instrument, (whether under seal or not,) which is _the foundation_ of a right sought to be enforced, is altered in a material part, even by a stranger, without the privity of the party affected by it, such alteration makes the instrument utterly void. The Scotch law respecting erasures is exceedingly stringent; and even goes farther than that laid down by Lord Widdrington. II. ESTOPPEL.--Both this doctrine, and that of erasures, as illustrated by this work, formed the subject of elaborate investigation in an article in the _American Jurist_ for 1842, (vol. xxvii. pp. 50, et sec.) The question relating to estoppel, is thus stated there in abstract terms. "If the son and heir-apparent of a tenant in fee-simple, conveys the land thus held, and afterwards dies in his father's lifetime, is the heir of the father, who also makes his pedigree through the son, estopped by that son's conveyance?" The conclusion arrived at is, that, according to Lord Coke, if such conveyance had been with warranty, the heir would be bound, if assets descended to him from the son.[A] But statute 4 and 5 Anne, c. 16 § 22, makes void as against his heir all collateral warranties made by an ancestor who has no estate of inheritance, in _possession_; and the Act just passed, (1844--stat. 7 and 8 Vict. c. 76 § 5,) permitting the alienation of contingent interests, expressly declares that it shall not enable any heir to dispose of his _expectancy_.