NO. 17. 



THE TENSION OF AQUEOUS VAPOUR. 



499 



THE TENSION OF AQUEOUS VAPOUR. 



THE DIURNAL PERIOD- 



The following Table gives the computed mean values of the vapour- 

 tension for each observation-hour and for each month of the drift of the 

 Fram, and the means for the month. 



From October, 1893, to March, 1894, we have observations for every 

 fourth hour. From April, 1894, to July, 1896, the observations of the hair 

 hygrometer and the corresponding observations of the temperature of the air 

 have made it possible to give determinations of the tension of vapour for the 

 night and morning hours not contained in the Tables of observation, and 

 thus to give complete results for every alternate hour of the day. 



mm. 



