If the applicant shall not begin his work within one year, and so far finish it within three years after such leave, as then to have his mill, manufactory, machine, or engine in good condition for use; or if such mill, manufactory, machine, or engine, be at any time destroyed or rendered unfit for use, and the rebuilding or repair thereof shall not within two years from the time of such destruction or unfitness, be commenced, and within five years from that time be so far finished as then to be in good condition for use, the title to the land so circumscribed shall revert to the former owner, his heirs, or assigns, and the leave so granted shall then be in force no longer, except as provided in § 62.1-126.