"Some years ago at Abercrombie and Fitch I bought a cattle caller, an
automobile horn manipulated by a lever with which nearly all cow emotions can be imitated, from the sweet lowing of a romantic heifer to the growling roar of a bull in the prime and lust of his bullhood. I had this contraption on Rocinante, and it was most effective. When its call goes out, every bovine within hearing distance raises its head from grazing and moves toward the sound."

---from 'Travels With Charley' by John Steinbeck