of Radioactive Products present in the Atmosphere. 829 



OX. From the values o£ h, k, and /jl which will be given 

 later on, it is found that 



•aTK — r = ^ , 8 cm. per sec. for A= 650 cm., and 



"4: XU X II 

 4:Llk 



— — -~ — r =40 , cm. per sec. for /i=150 cm., 

 •415 x h 



when the wires are charged at —11,000 volts. It will be 

 seen that a slight wind is sufficient to satisfy that condition. 

 (9) As a special case, if w = 0, cf> = const, represents a 

 system of circles which have their centres on the axis of c, 

 and yjr = const, another system of circles which pass through 

 A and have their centres on the ^-axis. In this case the 

 limits of integration with respect to </> are to be taken from 

 — co to 0, the value of <f> at the surface of the earth, where 

 the stream-lines end. Thus 



Q=^^(l-e-^f\d+. 



X A J^ L J 



Now, since d§i = sec 6 dr' = sec 6' dr, 



# =-2m(^-^) = - 4 ^^ 



Similarly, ds2=~-7~Tj l ty> 



CM 



• I fy'2 > 



) r 2 r f2 ] L 2 



00 16^FF^ = 2Msin^^ 1 ~^ C0t ^' 



diere % = 7r — (&' -#) = tt+ -, ^ . 



f 



Therefore 



Q 



f* {l-«- XA 2^k (1 - XC ° tX) }^. 



»/ — 7T *~ 



It may be noticed that the second term under the integral 

 sign diminishes rapidly as h increases. 



