i86 



WRIGHT: METHOD FOR PI.OTTING RECIPROCAL,S 



P. In the similar triangles ADO and CED (Fig. i) AD = i, 

 OD = X, CE = y' = BD = y, and OE = %' ; also OEICE = 

 ODIAD or 



x' = x.y and y' = >'. (i) 



The expression for a curve obtained in the one projection can 



Fig. I . — In this figure a series of straight lines are drawn through the origin and 

 the divisions of the ^-scale along FA , which has been displaced to unit distance 

 from the X-axis. The radiating lines correspond in this projection to the ver- 

 tical lines in the usual rectangular coordinate projection. Thus the point B of 

 the curve KB in the ordinary projection becomes the point C (intersection of the 

 ordinate Y with the radial line OA). 



be transformed to that for the corresponding curve in the second 

 projection by substituting in it for x' the value xy (equation (i)) 

 in the first expression. 



To illustrate the method and the significance of the projection 

 let the encircled points in figure i represent the data obtained in a 

 series of experiments and plotted in the usual manner on co- 

 ordinate paper. To ascertain the equation of the curve KB 

 which passes through these points draw the radiating lines {x') 

 from the origin through the X-scale plotted on the line (>' = i) ; 

 find the points of intersection of the ordinates y' (= y) with the 



