The dull sound was as if made by a fist, the tap by a finger-tip.
It was repeated.
Suddenly the girl jumped up with a little laugh. He was signalling to her and had sent "O.C."—her initials.
She tapped three times with her finger, struck once with the flat of her hand and tapped again. She had sent the "Understood" message.
Presently he began and she jotted the message on the margin of her book.
"Most urgent: Don't use soap. Bring it to office."
She smiled faintly. She expected something more brilliant in the way of humour even from Mr. Beale. She tapped "acknowledged" and went to bed.
"Matilda, my innocent child," she said to herself, as she snuggled up under the bed-clothes, "exchanging midnight signals with a lodger is neither proper nor lady-like."
She had agreed with herself that in spite of the latitude she was allowed in the matter of office hours, that she would put in an appearance punctually at ten. This meant rising not later than eight, for she had her little household to put in order before she left.
It was the postman's insistent knocking at eight-thirty that woke her from a dreamless sleep, and, half-awake, she dragged herself into her dressing-gown and went to the door.