IX, A, 1 



Wright and Smith: Radium Emanation 



69 



Table YIII. ^Cotnparison of day and night determinations of the radium- 

 emanation content of the atmosphere of Manila. 



Date. 



Duration of exposure. 



Ema- 

 nation 

 per cu- 

 bic me- 

 ter of 

 air ex- 

 pressed 

 in the 

 radium 

 equiv- 

 alent. 

 Grams 



X 1012. 



Date. 



Duration of exposure. 



Ema- 

 nation 

 per cu- 

 bic me- 

 ter of 

 air ex- 

 pressed 

 in the 

 radium 

 equiv- 

 alent. 

 Grams 



X 1012. 



53.50 

 69.20 

 67.60 

 69.39 



64.92 



From— 



To- 



Length 



of 



time. 



From- 



To- 



Length 



of 



time. 



1912. 



July 26-27 



Aug. 3-4 



Sept. 12-13 



Sept. 18-19 



Sept. 23-24 



Dec. 16-17 



Dec. 23-24 



1913. 



Jan. 2-3 



Jan. 8-9 



Jan. 20-21 



Jan. 26-27 



Jan. 30-31 



Feb. 10-11 



Feb. 12-13 



Feb. 17-18 



Mar. 11-12 



Mar. 18-19 



Mean of night 



p. m. 

 2.45 

 3.00 

 3.45 

 4.55 

 12.40 

 1.30 



='12.00 



3.00 

 1.00 

 5.15 

 12.30 

 1.00 

 1.30 

 1.30 

 1.30 

 1.00 

 5.30 



a. m. 



10.45 



"12.00 



11.45 



•>12.55 



8.40 



9.30 



8.00 



11.00 

 9.00 

 9.15 

 9.30 

 9.00 

 9.30 

 9.30 

 9.30 

 9.00 

 8.30 



hrs. 

 20.0 



81.06 



1913. 

 Jan. 16.- 



a. TO. 

 11.25 

 11.00 

 11.45 

 11.10 



p.m. 

 9.25 

 4.00 

 4.46 

 4.10 



hrs, 



10.0 



5.0 



5.0 



5.0 



21.0 84.10 



Jan. 22 



20.0 

 20.0 

 20.0 

 20.0 

 20.0 



20.0 

 20.0 

 15.0 

 20.5 

 20.0 

 20.0 

 20.0 

 20.0 

 20.0 

 15.0 



164.60 

 85.62 

 110.60 

 110. 60 

 137.60 



110.40 

 151.60 

 164.00 

 63.46 

 145.20 

 194.00 

 84.02 

 95.02 

 76.78 

 80.44 



114.05 



Jan. 24... 



Feb. 4 . . 



Mean of day 















1 



" Noon. 



" p. m. 



Although we have taken few entirely night exposures, the 

 observations which are so classified e^end throughout the entire 

 night. Generally, the exposure was started in the late afternoon 

 and extended until about the middle of the following forenoon. 

 The day runs were all taken in the afternoon, extending in one 

 case to 9.25 p. m. Although sufficient observations have not 

 been taken to draw any general conclusions, the difference 

 between the day and night exposures is too great to be explained 

 as entirely accidental. 



From the work of Simpson and Wright, Eve, and others on 

 the radioactivity of the air over the sea, it would naturally be 

 expected that for a place situated on the sea coast, where land 

 and sea breezes are more or less regular, the emanation content 

 of the atmosphere would be lower for the day than for the night. 



