Poole — Notes on the Distribution of Activity in Radium Therapy. 51 



Table 4. 



Six emanation tubes in long, coplanar, parallel serum needles, equally spaced 

 10 mm. apart, and partially withdrawn at intervals so as to distribute the 

 activity of each needle as uniformly as possible along a line 100 mm. long, 

 thus forming a rectangle 100 mm. x 50 mm. 



a = distance in millimetres from plane containing the four tubes. 

 & = ,, „ ,, " equatorial plane." 



The plane of the table passes midway between two tubes, so that for « = and 

 li < 50 the nearest tubes are at 5 mm. on either side. The maximum activity on 

 the surface of one of the needles (1"2 mm. diameter) would be 160 on the same 

 scale. 



