FORCES OF OBLIQUE WINDS ON TELEPHONE WIRES 589 



completion of the series of tests on each size of wire the test lengths 

 were cut out of the frame leaving about 2 inches of each wire at each 

 end and the series of tests repeated so that the net drag and net lift 

 figures could be determined. The purpose of leaving the short 

 lengths of wire at each end was to provide a correction for the inter- 

 ference efifects introduced at the ends of the wires. This practice was 

 probably effective as it will be shown later that, where comparisons 

 could be made, the results obtained in these tests agree satisfactorily 



Fig. 2 — Force components of wind on wires. 



Fd — Force along the direction of wind — drag. 



Fi = Force across the direction of wind — Hft. 



Fr = Resultant force. 



Fh = Force normal to the wire. 



Ft — Force along the wire — tangential. 



with those previously obtained. This is true even though the frame 

 comprised a fairly large proportion of the total resistance especially 

 when the angle between the wind and the frame was small. The case 

 when the wind and wires were parallel (tangential) has been omitted 

 from the results because of the large proportion of the total resistance 

 as well as the interference offered by the frame and because of its 

 relative unimportance to this study. 



Figure 2 shows the forces on the wires to which consideration has 



