126. Prescription.

Support for buildings may be acquired by prescription, either at common law or under statute1, but the existence of any contract between the parties or a grant inconsistent with the claim prevents its acquisition; thus no right can be acquired if the surface owner is, by some instrument, expressly excluded from the natural right of support2. Similar principles apply in the case of land weakened by excavation of the subjacent mines3; if the subjacent mines afford adequate support for buildings before excavation, no right is acquired by prescription against a lateral owner, if the prescription period