222 



THE ROYAL SOCIETY OF CANADA 



that the points lie on a series of straight lines, the slopes of which 

 decrease with increasing values of p. These straight lines would 

 appear to belong to a concurrent system as they all intersect at 

 approximately the same point. The mean position of the points of 

 intersection has been taken. It was found to have co-ordinates 

 (9.7, 1.94) so that the system of straight lines may be expressed as 

 1 .94 — logio(lOw) =^(9.7— c?) where k is the slope and is a function 



20O 



4O0 600 



P IN M MS or MERCURY 



of p. k was then calculated for different values of p and k plotted as 

 a function of p. This relatioin is given by the curve on chart 3. 

 By means of the equation 



1.94-logio (10w)=)^(9.7-(i) (1) 



and the {k,p) curve the depression of the centre of the disc can be 

 evaluated for any value of p between and 700 mms. of mercury and 

 any value of d between the limits 4 and 5 . 5 cms. 



