Her retort had neither disconcerted nor offended him. He was a philosopher--and, like so many of his kind, a laughing philosopher. When he was sufficiently recovered from his operation to get about on crutches he was the wag of the ward. He took a special delight in those practical jokes which are invented by patients to tease the nurses, and devoted the most painstaking ingenuity to their preparation. It was he who found a small hole in the lath-and-plaster wall which separates the ward from the ward's kitchen. Through this hole a length of cotton was passed and tied to the handle of a mug on the kitchen shelf. At this period, owing to the Zeppelin raids, only the barest minimum of light was allowed, and the night nurse, when she entered the kitchen, went into almost complete darkness. No sooner was she in the kitchen and fumbling for what she required than a faint noise--that of the cup being twitched by the cotton leading to the mischievous coster's bed--arose on the shelf and convinced her that she was in the presence of a mouse. She retreated, and perhaps if any convalescent patient had been awake she would have enlisted his aid to expel the mouse; but in the ward the patients were, as one man, snoring vociferously. It was this slightly overdone snoring, at the finish, which gave birth to suspicions and caused the trick to be detected. The night nurses do not have a placid time of it if their patients are at the stage of recovery when spirits begin to rise and the early slumber-hour which the hospital rules prescribe is not welcome. String-actuated knaveries, more or less similar to the mouse-in-the-kitchen one, are always devised for the plaguing of a new night nurse. Sometimes in the dead of night, when utter silence broods over the ward, the gramophone will abruptly burst into raucous music: its mechanism has been released by a contrivance which gives no clue to the crime's perpetrator. The flustered nurse gropes her way down the ward and stops the gramophone, every patient meanwhile sitting up in bed and protesting against her cruelty in having awakened them by starting it. Half an hour after the ward has quietened, the other gramophone (some wards own two) whirrs off into impudent song: it also has been primed. Nurse is wiser on future occasions: she stows the gramophones, when she comes on duty, where no one can tamper with them. Even so, she may have her nerves preyed upon by eerie tinklings, impossible to locate in the darkness; these are caused by two knives, hung from a nail fixed high up in the rafters. By jiggling a string, which is conducted over another rafter and down the wall to his pillow, the patient makes the knifeblades clash. Sometimes two strings, leading to different beds, complete this instrument of torture. After a determined search, nurse finds one string, and, having cut it, flatters herself that she has got the better of her enemies. Not a bit of it. She has scarcely settled in