twelve o’clock
From time to time , she heard Granny and Billy laughing . `` One of Billy 's jokes , '' she said to herself . Once she thought she heard the chirp of a bird , but she would not leave her work to find out what it was . When the twelve o'clock whistle blew , she called to Granny and to Billy to come to see the results of her morning 's labor . `` I say ! '' Billy emitted a long loud whistle . `` Oh , do you like it ? ''