To jigget = to jig, hop or skip; to jump about, and to fidget, cf.

Soon came the news that the folk of Vienna, who had been cutting up Europe as if it had been a jigget of mutton, had flown back, each to his own country, and that every man and horse in their armies had their faces towards France.

One curious point is brought out here in the phrase "boiled jiggets of mutton," which shews that the French gigot for a leg of mutton was formerly in use here.