376. The patient generally inquires whether, before bathing in the sea, it may not be proper to prepare himself by the use of a warm bath. I generally recommend a previous immersion in the tepid bath, at a temperature commencing at 90° Fahr., lowering five degrees each time, and terminating at 65°. Some laxative should be taken a few days before the course of bathing is commenced; but all violent purges must be cautiously avoided. I have known persons who, from a popular notion of the safety of purgation on such occasions, have taken violent doses of medicine, and been rendered extremely ill by their first immersion.

377. The warm bath is better calculated for those invalids whose re-action is not sufficient to sustain the shock of cold water. In such cases it will augment rather than diminish their natural strength and vigour; it will regulate the functions of the skin, promote the digestive powers, and concur with other measures to re-establish their health. To ensure objects so desirable, there are several precautions which it may be necessary to enumerate. As our purpose is not to induce profuse sweating, the temperature should not, on the first going into the bath, exceed 94° or 95°, but it may be gradually increased to 98°. In ascertaining its heat, we should never trust to our sensations; the thermometer is the only indication upon which we should rely. The most proper period for using the warm bath is an hour or two before dinner. If it be used during any of the ulterior stages of digestion, as in the evening, it will be liable to accelerate the circulation, and to produce disturbance. I have known persons, troubled with indigestion, to suffer considerable restlessness and irritation, by going into a warm bath just before bed-time; so susceptible, indeed, are some dyspeptics to the stimulus of heat, that the immersion of the feet alone in hot water, at this period, will be followed by a restless night.

The patient ought not to remain immersed longer than twenty minutes; and upon coming out, he may walk in the open air, but should be cautious not to occasion fatigue. Count Rumford has published an interesting essay on the subject of warm bathing, in which he observes that "a person may gain fresh health, activity, and spirits, by bathing every day at two o'clock in the afternoon, at the temperature of 96° or 97° Fahr., and remaining in the bath half an hour. He continued that plan for thirty-five days, and derived from it permanent advantage;" and he adds, "that the idea of going into bed after a warm bath, in order to prevent taking cold, is erroneous; that no alteration should be made in the clothing, and that the body, on exposure to the air, is not more susceptible of catching cold than it was before going into the bath." This coincides so perfectly with my own experience, that I feel it unnecessary to offer any further remarks upon the subject. Count Rumford also justly reprobates the idea of any advantage being derived from temperate baths of from 55° to 60°. The animal temperature, he observes, is 98°: in those temperate baths therefore, we lie motionless in a temperature inferior to that of our own bodies, and consequently must lose instead of acquiring heat, or even retaining that which we possessed.

378. Shower baths have been supposed to be more efficacious, in certain diseases, than baths of less partial application. In stating the result of my own experience upon this subject, I have to observe, that in debilitated habits they are not unattended with danger. I have certainly seen that species of indigestion which would seem to arise from, or be intimately connected with nervous irritability, greatly alleviated by the use of such partial baths, but I have generally recommended that the temperature of the water should be raised to 50°. Persons of a strong habit, who have been exhausted by intellectual exertion, are greatly resuscitated by such means.

379. Change of air is one of the most efficacious methods of curing dyspeptic complaints. The chemist has proved that the essential constituent parts of the atmosphere are the same in all places and situations; it has been collected in cities and in the country, on mountains and in plains, and even at the height of 7250 yards above the level of the sea, by Gay Lussac, in his aerial voyage in September 1805; but it has never been found perceptibly different in composition. From the latest and most accurate experiments, the proportions of oxygen and azote are 21 and, 79. It is indeed true, that various foreign bodies may be present, such as an increased quantity of carbonic acid, animal exhalations, smoke, etc. The quantity of aqueous vapour is also liable to constant variation. What then renders the air of some places so much more salubrious than that of others? or, whence arise the advantages which the invalid so constantly experiences from change of place? The proposition itself may, perhaps, be denied; and any attempt to establish an explanatory theory upon such a subject may be compared to that made by the Royal Society at the command of king Charles, to explain "why, if a vessel is filled brimful of water, and a large live fish be plunged therein, that it shall nevertheless not overflow." - Is it a fact? Is one situation more salubrious than another? and do dyspeptic patients actually derive any benefit from mere change of air? I do not imagine that any physician, who has practised a few years, will require any evidence of these facts beyond that which his own experience must have supplied.

It is notorious that children, who may be regarded in the light of sensible instruments, become unhealthy, if constantly confined to the air of large cities; robust and healthy persons are not so affected; but the delicate, and, above all, the dyspeptic invalid, is notoriously injured by it. Let him retire only for a few days into the country, and the effect which is produced by the change is too apparent to admit of any question. Some have supposed that the insalubrity of the air of a large city may depend upon the greater dampness and stagnation of the air, occasioned by its numerous buildings: I am not disposed to assert that such causes may not have a share in producing the effect; but the animal effluvia, and the carbonaceous matter so abundantly floating in the atmosphere, must also be taken into consideration. How does it happen that plants wither and die in a short time after they are brought from the nursery-grounds into the more capacious streets of the metropolis? Why should iron rust with so much greater celerity in London than in the country? These observations, however, merely go to prove that the air of a city is less pure than that of the country.