What is the test for determining the intention of a grantor in the event of an ambiguity in a description of a parcel of land?

The rules for ascertaining the intention of a grantor in the event of an ambiguity were set out in McPherson v. Cameron (1868), 7 N.S.R. 208, [1868] N.S.J. No. 2 (S.C.). Dodd J. said the general rule “is to give most effect to those things about which men are least liable to mistake” (para. 5). In applying this principle, the elements of the description are “marshalled” in the following order: “First, the highest regard had to natural boundaries; Secondly, to lines actually run and corners actually marked at the time of the grant; Thirdly, if the lines and courses of adjoining tract are called for, the lines will be extended to them, if they are sufficiently established; Fourthly, to courses and distances, giving preference to the one or the other according to the circumstances” (para. 5).