CLIMATE IN THE TREATMENT OF DISEASE  .—The most important qualities 'of the atmosphere in relation to health are (i.) the chemical composition, (ii.) the solids floating in it, (iii.) the mean and extreme temperatures, (iv.) the degree of humidity, (v,) the diathermancy, (vi.) the intensity of light, (vii.) the electrical conditions, (viii.) the density and pressure, and (ix.) the prevailing winds . Generally speaking, the relative purity of the air—i.e. absence of septic solid particles—is an important consideration; while cold acts as a stimulant and tonic, increasing the amount of carbon dioxide exhaled in the twenty-four hours . Different individuals, however, react both to heat and cold very differently . At health resorts, where the temperature may vary between 55° and 700 F.; strong individuals gradually lose strength and begin to suffer from various degrees of lassitude; whereas a delicate person under the same conditions gains vigour both of mind and body, puts on weight, and is less liable to disease . And a corresponding intensity of cold acts in the reverse manner in each case . Thus a health resort with a moderate degree of heat is very valuable for delicate or elderly people, and those who. are temporarily weakened by illness . Cold, however, when combined with wind and damp must be specially avoided by the aged, the delicate, and those prone to gouty and rheumatic affections . The moisture of the atmosphere controls the distribution of warmth on the earth, and is closely bound up with the prevailing winds, temperature, light and pressure . In dry air the evaporation from both skin and lungs is increased, especially if the sunshine be plentiful and the altitude high . In warm moist air strength islost and there is a distinct tendency to intestinal troubles . In moist cold air perspiration is checked, and rheumatic and joint affections are very common . The main differences between mountain air and that of the plains depend on the former being more rarefied, colder, of a lower absolute humidity, and offering less resistance to the sun's rays .

As the altitude is raised, circulation and respiration are quickened, probably as an effort on the

part of the organism to compensate for the diminished supply of oxygen, and somewhat more gradually the number of red blood corpuscles increases, this increase persisting for a considerable time after a return to lower ground . In addition to these changes there is a distinct tendency to diminished proteid metabolism, resulting in an in-crease of weight owing to the storage of proteid in the tissues . Thus children and young people whose development is not yet complete are especially likely to benefit by the impetus given to growth and the blood-forming organs, and the therapeutic value in their case rarely fails . For older people, however, the benefit depends on whether their organs of circulation and respiration are sufficiently vigorous to respond to the increased demands on them . For anaemia, pulmonary tuberculosis, pleural thickening, deficient expansion of the lungs, neurasthenia, and the debility following fevers and malaria, mountain air is invaluable . But where there is valvular disease of the heart, or rapidly advancing disease of the lungs, it is to be avoided . Light, especially direct sunlight, is of primary importance, the lack of it tending to depression and dyspeptic troubles . Probably its germicidal power accounts for the aseptic character of the air of the Alps, the desert and other places . Sir Hermann Weber has defined a " good " climate as that in which all the organs and tissues of the body are kept evenly at work in alternation with rest . Thus a climate with constant moderate variations in its principal factors is the best for the maintenance of health . But the best climate for an invalid depends on the particular weakness from which he may suffer . Pulmonary tuberculosis stands first in the importance of the effects of climate .

The continuous supply of pure fresh air is the main desideratum, a cool climate being greatly

superior to a tropical one . Exposure to strong winds is harmful, since it increases the tendency to cough and thus leads to loss of body temperature, which is in its turn made up at the expense of increased metabolism . A high altitude, from the purity and stimulating properties of the air, is of value to many mild or very early cases, but where the disease is extensive, where the heart is irritable, or where there is any tendency to insomnia, high altitudes are contra-indicated, and no such patient should be sent higher than some 1500 ft . Where the disease is of long standing, with much expectoration, or accompanied by albuminuria, the patient appears to do best in a humid atmosphere but little above the sea-level . The climate of Egypt is especially suitable for cases complicated with bronchitis or bronchiectasis, but is contra-indicated where there is attendant diarrhoea . Madeira and the Canaries are useful when emphysema is present or where there is much irritability of constitution . Bronchitis in young people is best treated by high altitudes, but in older patients by a moist mild climate, except where much expectoration is present . The influence of atmospheric conditions on the functions of the nose is very marked . Within the ordinary ranges of humidity and temperature the nasal mucous membrane completely saturates the air with aqueous vapour before it reaches the pharynx . In cold and dry mountain climates there is a very free nasal secretion, far beyond what is needed for the saturation of the air; and at low levels the reverse action takes place, the nose becoming " stuffy." The mechanism on which this depends is found in the erectile tissue, and anything favouring the engorgement of the veins, such as weak heart action, chronic bronchitis or kidney troubles, &c., leads to a corresponding turgidity of the nose and sinuses . In addition to barometric and other influences, it has been found that light produces collapse of this tissue, smoke having a similar effect . On this latter effect probably depends the fact that many asthmatics are better in a city like London than elsewhere, the smoke relieving the turgescence of the inferior turbinals of the nose .

In the treatment of pathological nasal conditions, all cases of obstruction from whatsoever cause are best in a dry atmosphere, and where there is

atrophy and a deficient flow of mucus in a moist atmosphere . If the mucous membrane is irritable a dry sheltered spot on a sandy soil and in the neighbourhood of pine trees is by far the best . Scrofulous children, namely, those in whom the resistance to micro-organisms and their products is low, pre-eminently require sea air, and had better be educated at some seaside place . Where the child is very delicate, with small power of reaction, the winter should be passed on some mild coast resort . Gouty and rheumatic affections require a dry soil and warm dry climate, cold and moist winds being especially injurious . For heart affections high altitudes are to be avoided, though some physicians make an exception of mitral cases where the compensation is good . Moderate elevations of 500 to 1500 ft. are preferable to the sea-level . In diseases of the kidneys, a warm dry climate, by stimulating the action of the skin, lessens the work to be done by these organs, and thus is the most beneficial . Extremes of heat and cold and elevated regions are all to be avoided .