DAILY VARIATION. 



177 



years can only be given at intervals of two hours, but these are sufficient for showing the 

 trend of the daily variation. 



Fig 59. Drily variation of pressure. McMurdo Sound, 4 years. 

 In order to bring out the dependence of the daily variation of the barometer on the 

 times of rising and setting of the .sun, the curves have been plotted in pairs on figure 59 

 so that months having similar solar conditions are brought into juxtaposition. 



