, 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