Exercise, in general, is such an agitation of the body, as produces salutary effects in the animal economy.

Exercise may be divided into two classes, active and passive: the former includes walking, hunting, dancing, running, leaping, swimming, riding on horseback, fencing, the military exercise, and, in short, all such games as require muscular exertions. Passive exercise comprehends riding in a coach, sailing, swinging, etc. ; all which we shall notice in their alphabetical order.

Exercise in the open air is, in every respect, preferable to that in houses, and close apartments. It ought, however, to be commenced and concluded in a gradual manner, and by no means abruptly. It should be continued only while we enjoy it without fatigue, and ought to be relinquished as soon as it becomes a task. The best time for this purpose is the forenoon, or some time before dinner, when the stomach is not too much distended : thus it increases the circulation of the blood; attenuates and divides the fluids ; and promotes a regular perspiration, as well as a due secretion of all the humours. It likewise raises the animal spirits, strengthens the muscular parts, creates appetite, and aids digestion. Hence those who take proper daily exercise, are in general robust, and afflicted with lew diseases.

On the other hand, violent exercise, or even fast walking, immediately before or after meals, is extremely pernicious ; for it impedes digestion, and impels to the surface of the body those fluids which are intended to promote the solution of aliment. - Immoderate exercise weakens the body, destroys the elasticity of the fibres, and necessarily accelerates both respiration, and the circulation of the blood; which may cause a variety of acci-dents, namely, the bursting of small blood-vessels, inflammations, and collections of blood towards certain parts of the body, such as the heart and brain. The saline acrimony of the fluids being thus more disengaged, the fat liquefies ; and ardent fevers, palsies, etc. are the melancholy consequences.

Of still greater importance is the exercise of children; for, on its proper regulation, their future health and straitmss, in a great measure, depend. This subject having very lately been perspicuously treated by Dr. Struve, we shall subjoin only a few elementary principles from his work on Physical Education: 1. Children ought to enjoy perfect liberty to move, leap, and take exercise at pleasure. 2. They should not be taught to rely on the assistance of others; but endeavour to make every effort consistent with their own strength. 3. When in the aft of falling, they ought not to be seized by the arm; and, after a fall, should not be too much pitied. 4. Every kind of spontaneous exercise is preferable to that taken by compulsion. 5. Exercise, though at an early period of infancy, must be uniform, that is, not confined to particular limbs of the body, nor at any time carried to excess. - We sincerely recommend these rules to the serious consideration of those who are engaged in the arduous and important task of rearing children ; as we are fully persuaded that, by a timely attention to those circumstances, many accidents, and much deformity, may be effectu-ally prevented.

Exercise. - Under this head, we have already enumerated the different kinds of exercise ; and their respective effects on the human body have been stated in the course of the present work. Many persons, however, being prevented from walking, riding, etc. in the open air, either by the inclemency of the weather, or from want of leisure, we have subjoined the following figure, representing a contrivance, that may serve as a substitute for dumb-bells.

The engine consists of a wooden cylinder, a, which turns on two central pivots, e, e, inserted in the upright posts. - b, b, are two rods, that may be made either of iron or of strong wood. These bars intersect each other at right angles, and are furnished with leaden weights at their extremities, c, c, c; which turn the cylinder with great velocity, when the rope d, attached to and passing round it, is pulled downwards. Farther, such weights draw the rope up again with considerable force, while it is wound backwards and forwards over the cylinder. - As this machinery may be fixed in a garret, or other spare-room at the top of a house, the rope may be conducted through the ceiling into a lower chamber ; so that sedentary persons, or invalids, may take sufficient exercise, without quitting their habitation, or exposing themselves to the vicissitudes of the weather.