Coat of arms of Horncastle

The blazon

erm. a chev. gu. on a chief vert, two towers ar. — Crest, a unicorn s head, erased, vert, armed and maned or, and charged on the neck with a trefoil of the last. [ Granted, in Ireland, {)th June, 1683.]

A blazon is the description of a coat of arms in the technical language of heraldry. The drawing comes from that text, and from nothing else.