six o'clock
Mary Beck looked pleased , and then a doubting look crept over her face . `` I do n't know any of the boys and girls very well except you , '' Betty explained , `` and Aunt Barbara likes the idea of having them come . Aunt Mary thinks that she ca n't come down , for the excitement would be too much for her , but I am going to tease her again as soon as I have time . It is to be a summer-house tea at six o'clock ; it is lovely in the garden then . Just as soon as I have helped Serena a little longer , you and I will go to invite everybody . Serena is letting me beat eggs . '' It was a great astonishment that Betty should take the serious occasion so lightly .