1878.] 
to Health and Comfort. 
199 
quantity of heat dispersed in breathing (on the previous 
supposition), account for one-half of the heat produced ; 
leaving one-half the heat to be dispersed in work, life, or 
conduction to air, or radiation to other bodies. These 
authorities quoted are, however, English, and it is uncertain 
what quantity of moisture is evaporated from the skin in 
heated rooms in mid-winter in our climate. 
It is probable that in still air, with the person in repose, 
the transfer of heat, either from the person or the clothing, 
whether from radiation or from conduction, is nearly equal ; 
but in any current of air or movement of the individual 
the effeCt of conduction will much exceed that from radia- 
tion. It should be remembered, however, that a current of 
air always exists about any person. The comfortable tem- 
perature of the air being lower than that of the person, 
there is established, by the heat imparted to the air by the 
person, an ascensional current surrounding and enveloping 
him, sufficiently defined to be measurable by a delicate ane- 
mometer, which is effective in augmenting considerably the 
conveCtion of heat over what would occur in entirely still 
air. Assuming any comfortable temperature for air between 
6o° to 8o°, the exhalations of breath, by virtue of extra tem- 
perature and the presence of vapour to saturation, notwith- 
standing the addition of some carbonic acid gas of greater 
density than that of the air, are still so much lighter than 
the air as to ascend at once after the directional impulse 
from the mouth or nostrils will have expended itself, which, 
when the aCt of breathing has its normal force, and is not 
made violent by running or exertion, occurs within two 
feet. 
In all cases the sensibility to loss of heat, whether from 
the breath as exhaled moisture or heated air, or from the 
person as evaporation from the skin, or as conduction to 
air, or by radiation to cooler objeCts, this sensibility, I say, 
varies in the several regards with different persons, with 
different races or nations, and, above all, with the habits 
from business pursuits or occupations, or the customs or 
fashions of the place of living ; any of which causes may 
and will have established a regime in each individual, and 
their comfort will depend upon conformity thereto. The 
occupation, business, or habits of individuals as regards 
their labour or exercise, both when at labour or exercise, or 
when at rest, cause much discrepancy in demands for heat. 
In the coldest and driest day, few young persons can fail to 
warm themselves to the point of comfort in skating ; many 
of the trades demand special temperatures for the workmen, 
