PROBABILITY THEORY AND TELEPHONE ENGINEERING 49 



Fig. 5 



The curves in Fig. 2 are chiefly useful for showing the form and 

 range of the relations rather than for the reading-off of individual 

 values; however, for the lower range oi R (R < I, say), they can be 

 read with very fair accuracy. Fig. 3 is merely an enlarged plot of 

 Fig. 2, over the R-range of about 1.5 to 3. The curves in Fig. 3 are 

 accurately readable except in the upper part of this i?-range; and the 

 deficiency there is compensated by the curves of Fig. 5 described in 

 the next paragraph. 



The curves in Figs. 2 and 3 were plotted by aid of the much more 

 accurately readable curves in Figs. 4 and 5, namely curves of R versus 

 the quantity pb,o{R' > R) defined by equation (20); thus, by aid 

 of (21), 



PbiR' > R) = p,,o(R' > i?) + exp (- i?2). (22) 



Fig. 5 is merely an enlarged plot of Fig. 4, over the i?-range of 1.4 

 to 3.0. 



The material of Fig. 2 is represented in alternative forms, which 

 are more convenient for some purposes, by Figs. 6 and 7, the former 

 giving curves of pbiR' > R) versus b with R as parameter, the latter 

 gi\-ing curves of b versus R with pb{R' > R) as parameter. 



The material of Fig. 4 is represented in one alternative form by 

 Figs. 8 and 9 each of which gives curves of pb,o{R' > ^) versus b with 

 R as parameter. 



Returning to Fig. 2, it will be noted that the curves cross each other, 

 but not at a common point; they cross rather diffusely in the neigh- 

 borhood of i? = 1.2. In the lower range of R, pb{R' > R) decreases 

 with increasing b; while in the upper range of R, it increases with 



