 Visiting ships in the 18th century brought cholera and smallpox . In 1727 , the loss of life was so high that too few residents remained to man the boats , and new families were brought in from Harris to replace them . By 1758 the population had risen to 88 and reached just under 100 by the end of the century . This figure remained fairly constant from the 18th century until 1851 , when 36 islanders emigrated to Australia on board the Priscilla , a loss from which the island never fully recovered . The emigration was in part a response to the laird 's closure of the church and manse for several years during the Disruption that created the Free Church of Scotland . 
