X. A, 1 Black'ivood: Radioactivity of Atmosphere 43 



Table I. — Diwnial variatum of active deposit — Continued. 



Date. 



Time af- 

 ter mid- 

 night. 



Recipro- 

 cal of 

 time for 

 leaf to 

 move 40 

 divisions. 



1914. 



May 4 — 



May 6 



Do 



Do 



Do - 



Do 



Do 



Do 



Do - 



Do -. 



Do 



Hrs. 

 234 

 h 



1* 

 2* 

 3i 

 44 

 6 



lOi 

 Hi 

 15 

 19i 



Relative 

 humidity, jji^g,.. 



tion. 



0.033 

 0.029 

 0.040 

 0.040 

 0.050 

 0.055 

 0.033 

 0.025 

 0.015 

 0.012 

 0.008 



Wind. 



73 

 79 

 81 

 80 

 80 

 83 

 80 

 70 

 72 

 48 

 68 



SE 

 Calm 

 Calm 

 Calm 

 Calm 

 Calm 

 Calm 

 WNW 

 WNW 



SE 

 ESE 



Force in 



kilo- 

 meters 

 per hour. 



6 



2 



3 



3 



3 



1 



2 



10 



16 



17 



7 



The wind, humidity, and active deposit were plotted as or- 

 dinates with the times after midnight as the abscissse. The 

 collection on windy days did not differ noticeably from those 

 taken in times of calm, and variations of the wind were not 

 accompanied by corresponding fluctuations in the deposit (fig. 

 5) ; so, apparently, variation of the wind velocity does not affect 

 the amount of active deposit collected. All the active deposit 

 curves show minima in the evening and maxima after midnight. 

 The depression shown in Dike's curve for early morning is 

 lacking in all of my observations. From the mean curves (figs. 

 2, 3, 4) it will be seen that there are corresponding variations 

 in the humidity and deposit, but the individual curves show that 

 minor variations of the humidity are not usually accompanied 

 by variations of the deposit, which indicates the existence of 

 other factors (fig. 5). One of these factors is the variation in 

 the emanation content, since Wright and Smith ^* have found 

 that the night emanation content at Manila, as measured by 

 the charcoal absorption method, is about twice that of the day. 



DIURNAL VARIATION AT A HIGH ELEVATION 



Observations of the active deposit were made on Mount Ma- 

 quiling, 60 kilometers from Manila, at an elevation of about 

 1,140 meters. The apparatus was similar to that used at Manila 

 except that the guard ring was eliminated. The electroscope 



This Journal, Sec. A (1914), 9, 68. 



