The power of generating heat in warm-blooded animals is at its minimum at birth, and increases successively to adult age; young animals, instead of being warmer than adults, are generally a degree or two colder, and part with their heat more readily; facts which cannot be too generally known. They show how absurd must be the folly of that system of "hardening" the constitution (to which reference has been before made), which induces the parent to plunge the tender and delicate child into the cold bath at all seasons of the year, and freely expose it to the cold, cutting currents of an easterly wind, with the lightest clothing. The principles which ought to guide a parent in clothing her infant are as follows:-- The material and quantity of the clothes should be such as to preserve a sufficient proportion of warmth to the body, regulated therefore by the season of the year, and the delicacy or strength of the infant's constitution. In effecting this, however, the parent must guard against the too common practice of enveloping the child in innumerable folds of warm clothing, and keeping it constantly confined to very hot and close rooms; thus running into the opposite extreme to that to which I have just alluded: for nothing tends so much to enfeeble the constitution, to induce disease, and render the skin highly susceptible to the impression of cold; and thus to produce those very ailments which it is the chief intention to guard against. In their make they should be so arranged as to put no restrictions to the free movements of all parts of the child's body; and so loose and easy as to permit the insensible perspiration to have a free exit, instead of being confined to and absorbed by the clothes, and held in contact with the skin, till it gives rise to irritation. In their quality they should be such as not to irritate the delicate skin of the child. In infancy, therefore, flannel is rather too rough, but is desirable as the child grows older, as it gives a gentle stimulus to the skin, and maintains health. In its construction the dress should be so simple as to admit of being quickly put on, since dressing is irksome to the infant, causing it to cry, and exciting as much mental irritation as it is capable of feeling. Pins should be wholly dispensed with, their use being hazardous through the carelessness of nurses, and even through the ordinary movements of the infant itself. The clothing must be changed daily.--It is eminently conducive to good health that a complete change of dress should be made every day. If this is not done, washing will, in a great measure, fail in its object, especially in insuring freedom from skin diseases. IN CHILDHOOD.--The clothing of the child should possess the same properties as that of infancy. It should afford due warmth, be of such materials as do not irritate the skin, and so made as to occasion no unnatural constriction.