Two or three times daily, while the baby is out of the room, the windows should be opened wide to air the room thoroughly, one of these airings being just before the baby is put to bed for the night. The doctor’s usual instructions concerning the temperature of the nursery are to keep it from 68° F. to 70° F. during the day and about 65° F. at night, during the first three months and lower it gradually to 64° F. during the day and about 55° F. at night as the baby grows older. It is customary to begin to open the nursery window at night when the baby is three or four months old, if he is well and the temperature is above freezing. In planning to take the baby out of doors it is wiser, as a rule, to begin with the indoor airing when he is about a month old, except, of course, during the moderate or mild months of the year, when he is taken out at once. If the weather is cold, the baby may be protected with extra wraps and carried in the arms, into a room in which the windows are open and kept there for fifteen or twenty minutes. This indoor airing is increased by being gradually lengthened to two or three hours and by having the windows opened wider and wider. By the time he is two or three months old he is taken out of doors on clear, bright days, the best time being between ten and three o’clock, when the sun is high. If he is carried in the nurse’s arms at first the warmth of her body serves as a protection and helps to accustom him to the out-of-door life, when he spends a good deal of his time out of doors in his carriage. On windy, stormy days or when there is melting snow on the ground, the baby may be given his airing on a protected porch or in a room with the windows open. He is not usually taken out if the temperature is below freezing until the third or fourth month. After this time the average baby is taken out when the temperature is not lower than 20° F. When the baby is dressed in his extra wraps he must be taken out of doors or the windows opened immediately, for otherwise he will become overheated and be in danger of chilling when taken into the colder air. Warm hands and feet, a good color and the baby’s tendency to sleep most of the time while out of doors are evidences of his being adequately clothed for his airing, while the reverse is true if he is not warm enough.