Sioux City Academy of Science and Letters. 53 
bad, and in one of which the conditions were favorable, 
showed 6.92 parts of CO, present. In Whittier 8.56 
parts were found, and in Cooper 9.62 parts. 
Authorities agree that 7 parts in 10,000 is permis- 
sible and that much beyond this point constitutes an 
injurious if not a dangerous condition. 
The results of these tests sustain quite generally the 
theories regarding ventilation. It is held that the only 
true and successful system for all kinds of weather and 
atmospheric conditions is one in which a rotary fan or 
other propelling device forces a constant and pure stream 
of air into the rooms. Such a system is found at the 
High School building and that is the only school build- 
ing thus equipped in the city. The results of the air 
tests from this building, showing 6.85 parts of carbon 
dioxide in 10,000 parts of air, are very satisfactory. 
In the Longfellow building the results were quite 
satisfactory also, and in this building as in many others 
in the city the Smead system is used for heating and 
ventilating, but unlike the Smead system of the High 
School there is no rotary fan, the movement of the air 
currents being secured by gravity methods. The dis- 
tinct benefit of this system is in getting the air supply, 
both for hot and cold air, directly from outdoors, a lever 
in the room permitting the teacher to regulate the sup- 
ply as to kind—hot or cold—but in all cases pure air from 
out of doors. All the air passes out of the room through 
outlets connecting with a separate flue which passes up 
alongside of the furnace chimney and thus out of the 
building at the top. There is thus a steady stream of 
pure air entering the rooms and a steady stream of the 
vitiated air passing out and away from the building. 
This system, however, will secure best results only 
in cold weather when there is a marked difference in the 
temperatures of the outer air and the air within the 
rooms, for when the temperature without is nearly or 
fully equal to that within, the ascending current from the 
room are both retarded, if not entirely stopped, and 
since the efficiency of this system, or any system depends 
upon the facility with which the air may be renewed in 
the rooms, the result is that the ventilation is much less 
perfect in spring and fall than in winter. 
