Correspondence mainly concerns Ewart's research on the inheritance of callosities in horses, on prehistoric horses and on the Celtic and Connemara ponies. Letters from Sir William Ridgeway and Matthew Horace Hayes discuss their own research projects, and there is also various correspondence with professors within the University of Edinburgh discussing possible expansions to various University departments. Many letters, such as those from the Foreign Office, also reflect Ewart's role in the increasing number of zebras and zebra hybrids being exported to India and Africa for the use in the military and as beasts of burden.

This series also contains five sale catalogues for Wilfrid Scawen Blunt's horse sales for the years 1897-1901.