Definition of "in use"

The man, ye should ken, was cast upon a rock in the sea, where it appears the Good People were in use to come and rest as they went through to Ireland.

1886 May 1 – July 31, Robert Louis Stevenson, Kidnapped, being Memoirs of the Adventures of David Balfour in the Year 1751: […], London, Paris: Cassell & Company, published 1886