Coat of arms of Bowater

The blazon

ar. on an inescocheon, sa. betw. eight martlets gu. a crescent ar.— Crest, out of the clouds, a rainbow, all ppr. [Heralds' Office, London, C. 24.]

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.