This stone is heavily encrusted with lichen and virtually illegible. The Cowper & Ross transcript is faulty, giving Peter's age at death as 70 (he was 76) and Barbara Mackay's death as 1878 (she died 1898). The information should be:
PETER MACKAY,
Strathen,
died 22nd June 1902
age 76.
And his wife,
BARBARA MACKAY,
died 8th April 1898
age 59.