Unveiled in 1888, Royal Arsenal's first crest featured three cannon viewed from above, pointing northwards, similar to the coat of arms of the Metropolitan Borough of Woolwich (nowadays transferred to the coat of arms of the Royal Borough of Greenwich). These can sometimes be mistaken for chimneys, but the presence of a carved lion's head and a cascabel on each are clear indicators that they are cannon. This was dropped after the move to Highbury in 1913, only to be reinstated in 1922, when the club adopted a crest featuring a single cannon, pointing eastwards, with the club's nickname, The Gunners, inscribed alongside it; this crest only lasted until 1925, when the cannon was reversed to point westward and its barrel slimmed down.
What was the Arsenal crest from 1913 to 1921? (If the question is unanswerable, say "unanswerable")
unanswerable