1856,Emmeline Stuart-Wortley,The Sweet South, London: Printed for Private Circulation: Volume 2, Chapter 14, p. 173,[1]
We met several camelestrians on our road, and horsemen andassmen; and the scenery in many parts was very pretty.
1885,George Manville Fenn, chapter 15, inDick O’ the Fens[2], London: Blackie & Son, published1888, page244:
No sooner was Tom upright than the donkey gave the whole of his skin and muscles a wrench sidewise, which felt as if the seat was being dragged away. ¶ The consequence was that Tom nearly went off to the right. He was too good anassman, though[…]
Even the asses have a fashionable air, large white beasts loaded with cushions, fringes, and tassels; so that horsemen andassmen trot side by side on equal terms in the gay parade.