four o'clock
`` Oh , yes , '' replied Dorothy ; `` I could do that easily . '' `` How ? '' asked Aunt Em . `` Ozma sees me every day at four o'clock , in her Magic Picture . She can see me wherever I am , no matter what I am doing . And at that time , if I make a certain secret sign , she will send for me by means of the Magic Belt , which I once captured from the Nome King . Then , in the wink of an eye , I shall be with Ozma in her palace . ''