Whistles

     Recently I've read four novels about the Bow Street Runners during the Regency period in Great Britain.
     For those not in the know, the Bow Street Ruuners were the police officers in Greater London before the establishment of the Metropolitan Police in London.
     In three of the four novels the Runners were described as blowing their police whistles to call for help.
     The fact of the matter is that the Bow Street Runners and the Metropolitan Police did not use whistles until the 1880s when the force adopted the Metropolitan whistle made by Acme Whistle, Before that the police used a rattle type contraption to call for help. The rattle, perhaps, was heard a quarter mile away. The Acme whistle was heard over more than a mile away.
     Bow Street, since it was really made up of a bunch of "thief-takers" probably didn't use anything to call for help because there were so few of them for many years. They certainly didn't use whistles.