830 S. Kinoshita, S. Nishikawa, and S. Ono on Amount 

 On evaluation it was found that 



Q = -25 x4tt^ X ^_ e for 7i = A a = 150 cm., and 



Q = • 75 x 47T/A] h -\—^ for 7i = hi = 650 cm. 



(10) When the wind is in any other horizontal direction 

 we can consider separately the effects of two component 

 velocities w s and w p perpendicular and parallel to the direc- 

 tion of the wire respectively, the latter of which, however, 

 will have no effect on the value of Q, the case being the 

 same as that in which there is no wind. We may, therefore, 

 conclude that the number of the particles of radium A deposited 

 per second on each centimetre of the wire is 



4yul n , 7 X E N E 



.„ = <±fJUlt n , , /V E i\ E , 



it w s / -~f- T > y ~ 47r/x A . ■ — - — - , and 



lf ° \ Ws \ ^1 ' ' 2s> * ^ k -xT ^ Q \ ^ k ■ -XT' 



for h = 150 cm., 



-, ~ K . 7 XeNe — n — . 7 XrNe 

 and ' id X 4.7TfiK . — \ SJ \ Att/jl/c . — — , 



A A A-A 



for 7/ = 650 cm. 



(11) The result can be obtained from another consideration. 

 From the equations already obtained for the boundary curves 

 RP and RiP , it is easily seen that the depth of the effective 



4 TT Li/c 



region is - — — at x= - cc , for which 6' — 6 =^2tt. provided 



that the curve RP Ri does hot cut the axis of x at a finite 

 distance. Since the velocity of the particles at x = -co is 

 w s and in the direction of the ^-axis, 



Att/jlJc 



— - — . 10s = VWak 

 W s 



is the quantity of air which crosses the section of the effective 

 region of unit width at x= -co in the direction of x in each 

 sec, or, in other words, the quantity of air contributing to 



the deposit on each cm. of the wire per second. Since — - — 



A A 



is the number of atoms of radium A in each cubic centimetre 



