"tightrope," 1895, from high (adj.) + wire (n.).
I looked in at the Alhambra the other night, and found an excellent show, notably, a high-wire act by Mdlle. Virginia Aragon. A very handsome Spaniard with coal-black tresses, she does her work with great neatness. The best thing she does is to kneel on the wire, and, leaning forward, pick up with her teeth from between her knees, a handkerchief. Then she swings on the wire, balancing herself with one foot only. Altogether, she is the smartest wire-walker I've seen for many a day. Her sister, by the way, is a trapezist and figured at the Empire not long ago. ["The Sketch," Nov. 27, 1895]