to Health and Comfort . 
219 
1878.] 
same as if he or she were to maintain the same temperature 
through active exercise and warm clothing out of doors. 
The exception expressed by “ very nearly ” relates to the 
clad portion of the body — the obstacle presented by the 
clothing to the free diffusion of aqueous vapour is more 
effective between the cold air which is but little warmed to 
demand moisture, and the skin which will give it out if the 
vacuum demands it, than between the arid air of the room, 
which takes up every particle of moisture as it transpires 
through the clothing. As regards loss of moisture from 
the throat or lungs, however, there is absolutely no differ- 
ence in breathing the air of the supposed room and that 
which is then found out of doors, although the one be at 
70° to 8o° and the other at zero ; reiterating the former 
statement : — “ In either case the exhaled breath is at 90° as 
it passes out from the nostrils or lips, and is saturated or 
nearly saturated with moisture.” No one ventures to assert 
that it is unhealthy, as an aCt of breathing, for the human 
race to breathe freely the coldest dry air of winter, because 
of the supplying of moisture to the anhydrous air. There 
is an evident fallacy in the assumption that it can be 
healthy to check instantly that copious secretion which has 
been supplying moisture to the fresh cold air of zero, by 
going into a room of summer hygrometric condition, or to 
demand such an effort of the tissue of the lungs suddenly 
by leaving such a room for the outer air. Fortunately, 
Nature is more lenient than the theorists, and we do not 
get 70° to 8o° with 70 per cent, of saturation in the most 
unventilated or uncomfortably heated houses, and with all 
efforts to the contrary, even 40 per cent, is of unusual 
attainment when the external air has a temperature of zero. 
It must be admitted, however, that some small degree of 
hydration is a necessity for comfort, and, with comfort for a 
demand, some reason may be found to establish the health- 
fulness of the small supply. It is certain from all experience 
that from 5 to 10 per cent, of moisture can be added to air 
after it is heated, certainly with much relief, especially to 
the eyes, with apparently little harm, although such addition 
may make the occupant of a heated room a little delicate 
as to out-door exposure. Moisture may to some small 
extent be abstracted by the means of heating, especially 
when the heating is by stoves or hot-air furnaces ; at all 
events, the presence of a sheet or surface of water over 
which the heated air is allowed to pass is now a recognised 
means of supplying a small quantity of aqueous vapour to 
air of ventilation. But the quantity supplied in this way is 
