588 BELL SYSTEM TECHNICAL JOURNAL 



of 10 miles per hour. The readings so obtained are here studied and 

 analyzed. 



The wire set-up used in the wind tunnel is shown in the accompanying 

 picture (Fig. 1) and is similar to that used by Eiffel.* It comprised a 

 five-foot frame of 0.v3 75-inch diameter steel in which five wires of either 

 the 0.104-inch or 0.165-inch size were mounted. A spacing of 2.75 

 inches was used between the centers of the wires. The frame of wires 



Fig. 1 — Wind tunnel setup. 



was installed in the approximate center of the nine-foot section of the 

 tunnel with the shorter axis of the frame in a horizontal plane and 

 perpendicular to the axis of the tunnel. This arrangement was 

 convenient for connections to the weighing mechanism and permitted 

 the frame to be rotated about its short axis. 



During each step in the test the horizontal (drag) and vertical (lift) 

 forces on the frame of wires were measured at least three times. At the 



