of Oxygen Absorption Lines in the Solar Spectrum. 201 

 FIG. 1. 



(O 



the group, which, is divided into four series. Ordinates are thent 

 drawn in the position occupied by each line. The axis of y is divided 

 into a number of equal parts, 1, 2, 3, n. Lines parallel to the axis of 

 x, drawn from each of these divisions, intersect the respective 

 ordinates. The continuous curve passing through the points of inter- 

 section is found to possess all the properties of a parabola. 



Three points at least are selected to determine the position of the 

 vertex and value of latus rectum. The distance from the origin along, 

 y is also found for an ordinate to the first line of a series. 



p 2 



