It shall not be lawful to the parties in whose favour such feu charter or lease shall have been granted, or their successors, to divert the land so feued or leased, or the buildings erected thereon, to any other purpose than the purpose for which the same shall have been feued or leased; and if such land or buildings shall at any time be so diverted, or shall be, for the period of five years, left unemployed for the purposes for which the same were feued or leased, it shall be competent for the heir of entail in possession for the time being to apply by petition to the sheriff of the county in which the land or buildings lie, setting forth the diversion or abandonment, and praying to have the feu charter or other right or lease declared to be forfeited, and the land therein contained, with the buildings erected thereon, to belong to the heirs of entail of the estate in relation to which such feu charter or lease was granted, in all time thereafter, free from and unaffected by such feu charter or lease, and to be again subject to the destination and fetters of the entail of such estate; and the said sheriff, after ordering intimation of such petition to the parties at the time in right of such feu charter or lease, if known, and also public notice to be affixed on the door of the parish church of the parish within which the land feued or leased is quoad sacra situated, for three successive Sundays, shall, on evidence of such intimation and publication being produced to him, resume consideration of the petition, and shall inquire into the alleged diversion or abandonment, and shall hear the parties in the right of the feu charter or lease, or any of the inhabitants of the parish for whose behoof the land is held, and receive any competent evidence that shall be offered by any of the parties interested; and if he shall find the allegation of diversion or abandonment proved, he shall pronounce a deliverance to that effect, and shall declare the feu charter or lease forfeited, and the portions of ground therein contained to belong to the heirs of entail aforesaid, in all time thereafter, free from and unaffected by such feu charter or lease, and subject to the destination and fetters of the entail of the estate in relation to which such feu charter or lease was granted; and such decree of declarator shall be recorded in the general register of sasines, and the land and subjects to which the same relates shall be thereafter possessed by such heirs of entail accordingly, and as if such feu charter or lease had never been granted.