DISCUSSION OF THE VERTICAL FORCE. 



15 



Total number of observations used, 22092 



larger disturbances, 2097 



Ratio of disturbances to observations, 1 to 10.5 



Investigation of the eleven year (also called ten year] period in the inequality of the 

 amplitude of (lie Diurnal Variation of the Vertical Force. The preceding monthly 

 means of the bi-hourly and hourly normals were rearranged in four groups of one 

 year each, necessarily omitting the first five months ; the annual means have for 

 their mean epoch, January, as the monthly means were arranged from July to July. 



The means for the year 1842-43 depend on nine months only, to refer them to 

 the mean of twelve months, the differences for every observing hour, between the 

 same nine months and twelve months for the preceding and following year, were 

 made out and the mean correction, giving the weight two to the following year, as 

 indicated by the readings taken at the hour 14, was applied to the values of 1842-43. 



