About nine o’clock
`` I 'm off , then , '' and Polly threw herself flat on her sled . It was great sport . The track was so icy that the runners made sparks as the sleds whizzed down the steep hill . About nine o'clock Mrs. Baird stole from the Assembly Hall and sought the rest of her own room . She had grown fearfully tired of Miss Tilden-Brown 's endless talk , and heartily sorry for the girls . As she reached her dainty chintz-hung sitting-room , she lifted the window and stood looking at the big full moon and breathing the cool night air . Presently a joyous laugh rang out , followed by another .