TELEPHONE LINE WIRE SPACING PROBLEMS 



217 



Fig. 12. The standard deviation shows a tendency to increase as the 

 angle of deflection is increased. However, as might be expected from 

 the use of natural winds for the experiments in place of the steady wind 



m 



s 



2 24 

 < 



u. 20 



AVERAGE EXPERT 



MENTAL ANGLE a' 



I 



a' -30-' 



O 8 



THEORETICAL ANGLE a= 16.5 

 NUMBER OF EXPERIMENTAL ANGLES 

 PER CELL = 20 



3 SIGMA LIMITS FOR SINGLE OB- 

 SERVATIONS AND FOR AVERAGES 

 OF 20 OBSERVATIONS WERE CAL- 

 CULATED WITH RESPECT TO _ 

 AVERAGE EXPERIMENTAL ANGLE a' 

 THESE LIMITS ARE SHOWN AS: 

 a.'±3(J' FOR SINGLE OBSER- 

 VATIONS 



a'± 4=- FOR AVERAGES OF 20 



V20 

 OBSERVATIONS 



WIRE —0.165-INCH DIAMETER 

 COPPER 



a' + 3a' 



10 12 14 16 18 20 22 24 26 28 

 EXPERIMENTAL ANGLE (a') IN DEGREES 



30 32 34 36 38 



Fig. 1 1 — Distribution of experimental angles of deflection of a suspended wire in a 

 transverse wind velocity cell of 25.1 to 27.0 miles per hour. 



assumed in the theory, there was irregularity in the "three-sigma" 

 limits. For this reason a regression line was determined for all the 

 points in each particular "three-sigma" limiting group and the lines 

 were drawn. This graph shows the agreement between the angle of 

 deflection of the wire as determined by the experimental method and 

 that given by the theoretical equation (1). The area between the 

 two extreme limit lines represents approximately the range within 

 which single values determined experimentally would be expected to 

 fall. Likewise, the area between the two inner limit lines represents 

 approximately the range within which averages of 20 values for a 

 particular wind velocity cell would be expected to fall. 



In general, the results indicate that the theory for the equilibrium 

 position of a suspended wire under the influence of an assumed steady 

 transverse wind is applicable within reasonable limits to a wire sub- 

 jected to the varying conditions of natural winds. 



, An Accelerated Method of Test 



Testing the merits of various arrangements in natural winds is a 

 slow procedure in which it is necessary to await the course of nature. 



