2 Trans. Acad. Sci. of St. Louis. 



An obstacle which wholly checks the wind, would develop 

 this pressure on its windward surface.! This is the pressure 

 collected by an open tube directed by a wind-vane. I have 

 verified this formula by experiments on railroad trains and 

 find it very exact. 



In pressure-board work, the experimenter determines by 

 means of calibrated springs, the total force required to hold 

 the board against the wind, and divides this force by the area 

 of the board. This gives an average pressure. And here the 

 result is due to a summation of compression on the windward 

 side, and rarefaction on the leeward side. In the tube col- 

 lector, the effect of rarefaction is wholly eliminated. 



It is not uncommon to hear statements that the want of 

 agreement of different observers in their determination of the 

 constant in eq. (2) is very unsatisfactory. Part of this dis- 

 agreement is due to the fact, that the phenomena were 

 essentially different. 



Neither the tube collector nor the pressure-board yields 

 any information of value concerning the distribution of wind- 

 pressures over buildings, or other structures. It is this 

 information which the writer has sought to obtain. 



The pressure of the quiescent air in a building, against the 

 inner surface of its walls, is given by a barometer. In a wind 

 storm, the air masses surging against the building, and sweep- 

 ing around it, compress the air on the windward side, and 

 produce a rarefaction on the leeward side. These differences 

 in pressure are continually changing, as the wiud velocities 

 change, and they are continually dissipating by a flow of air 

 into and out of the building. This flow takes place, not only 

 through windows, doors and crevices, but apparently through 

 heavy brick walls and plastered interiors. I have found by 

 methods that will appear later, that in a tightly closed brick 

 house, the effect of wind is to increase the pressure within the 

 building. This was the case when windows and doors were 

 provided with weather strips, and two stoves were burning on 

 the first floor, and an open grate fire was burning on the 

 second floor where the internal pressure was taken. The air 

 was rushing upward in the chimney leading from the open 

 grate with such velocity as to yield the fluttering sound which 



t Newton's Theorem. 



