These whistles, very light, weighing a few grams, are attached to the tails of young pigeons soon after birth, by means of a fine copper wire, so that when the birds fly the wind blowing through the whistles sets them vibrating, and this produces an open air concert, for the instruments in the same flock are all different. On a serene day in Peking, where these instruments are manufactured with great cleverness and ingenuity, it is possible to enjoy this aerial music while sitting in one’s room.