METEOROLOGICAL OBSERVATIONS 



481 



DIURNAL VARIATION IN ATMOSPHERIC PRESSURE 



The barograms at Cape Flora have been reduced to the aneroid barometer used at this 

 station and the mean daily curves for each month deduced graphically. The values of the 

 diurnal variation thus obtained are given in the following tabulation, pressures greater than 

 mean of day being indicated by plus signs, and vice versa. 



Summary of mean monthly diurnal variation in atmospheric pressure at Cape Flora 

 From barograms June, 1904, to May, 1905 



As the above results depend upon an aneroid barometer on which correction to standard 

 was obtained only before and not after the completion of the work, and as the constancy of 

 adjustment of the instrument is in doubt, it has not been thought advisable to make any 

 extended reductions from the Cape Flora results. Formulae representing the diurnal variation 

 have been derived from the observations, as above, by means of Bessel's periodic function (see 

 page 289) to terms of the third order. The resulting amplitudes and phase angles are shown 

 in the following table, and the curves computed from the same are represented in figure 4. 



