ON THE 



LUNAR ATMOSP HERIG TI DE 



AT BATAVIA, 



HY 



P. A. BEBQSMA. 



Since January l st , 1866, hourly observations of the baro- 

 metric pressure of the Atmosphere have been made at the 

 Batavian Observatory every day except on Sunday. The ob- 

 servations made from January 16 t]l , 1866, to January 12 th , 

 1869 have been discussed with the view of investigating the 

 influence of the inoon's position, relatively to the meridian, 

 upon the baromefric pressure. 



General sabine discussed, with the same object, the hourly 

 observations of the barometric pressure made at St. Helena 

 from October 1843 to September 1845 inclusive, and decidedly 

 proved the existence of the Lunar Atmospheric Tide at 

 St. Helena (See Phil. Trans, for 1847, I, 45). 



The method used by General sabine in the discussion of 

 the St. Helena observations was the following- — 



If b be called the height of the barometer at 0° C at any 

 hour of observation, and b' the mean height of the barometer 

 at the same hour during the month to which the day belongs, 

 then b — b' is a quantity which remains, after the approximate 

 diurnal variation has been eliminated. The amount of b — b' 

 depends on many causes, amongst others on the influence 

 of the moon upon the barometer, if this influence be not the 

 same at the corresponding solar hours of the different days. 

 The values of b — b' were calculated for each hour of obser- 

 vation. 



